feat(pdfengines): add watermark and stamp feature

.agents/TESTER.md

@@ -26,7 +26,7 @@ make test-integration TAGS=chromium-convert-html
 make test-integration TAGS="merge,split"
 ```
 
-Available tags: `chromium`, `chromium-concurrent`, `chromium-convert-html`, `chromium-convert-markdown`, `chromium-convert-url`, `debug`, `health`, `libreoffice`, `libreoffice-convert`, `output-filename`, `pdfengines`, `pdfengines-convert`, `pdfengines-embed`, `embed`, `pdfengines-encrypt`, `encrypt`, `pdfengines-flatten`, `flatten`, `pdfengines-merge`, `merge`, `pdfengines-metadata`, `metadata`, `pdfengines-split`, `split`, `pdfengines-bookmarks`, `bookmarks`, `prometheus-metrics`, `root`, `version`, `webhook`, `download-from`.
+Available tags: `chromium`, `chromium-concurrent`, `chromium-convert-html`, `chromium-convert-markdown`, `chromium-convert-url`, `debug`, `health`, `libreoffice`, `libreoffice-convert`, `output-filename`, `pdfengines`, `pdfengines-convert`, `pdfengines-embed`, `embed`, `pdfengines-encrypt`, `encrypt`, `pdfengines-flatten`, `flatten`, `pdfengines-merge`, `merge`, `pdfengines-metadata`, `metadata`, `pdfengines-split`, `split`, `pdfengines-watermark`, `watermark`, `pdfengines-stamp`, `stamp`, `pdfengines-bookmarks`, `bookmarks`, `prometheus-metrics`, `root`, `version`, `webhook`, `download-from`.
 
 Other useful flags:
 

Makefile

@@ -195,6 +195,10 @@ NO_CONCURRENCY=false
 # metadata
 # pdfengines-split
 # split
+# pdfengines-watermark
+# watermark
+# pdfengines-stamp
+# stamp
 # pdfengines-bookmarks
 # bookmarks
 # prometheus-metrics

go.sum

@@ -166,8 +166,6 @@ github.com/microcosm-cc/bluemonday v1.0.27 h1:MpEUotklkwCSLeH+Qdx1VJgNqLlpY2KXwX
 github.com/microcosm-cc/bluemonday v1.0.27/go.mod h1:jFi9vgW+H7c3V0lb6nR74Ib/DIB5OBs92Dimizgw2cA=
 github.com/mikelolasagasti/xz v1.0.1 h1:Q2F2jX0RYJUG3+WsM+FJknv+6eVjsjXNDV0KJXZzkD0=
 github.com/mikelolasagasti/xz v1.0.1/go.mod h1:muAirjiOUxPRXwm9HdDtB3uoRPrGnL85XHtokL9Hcgc=
-github.com/minio/minlz v1.0.1 h1:OUZUzXcib8diiX+JYxyRLIdomyZYzHct6EShOKtQY2A=
-github.com/minio/minlz v1.0.1/go.mod h1:qT0aEB35q79LLornSzeDH75LBf3aH1MV+jB5w9Wasec=
 github.com/minio/minlz v1.1.0 h1:rUOGu3EP4EqJC5k3qCsIwEnZiJULKqtRyDdqbhlvMmQ=
 github.com/minio/minlz v1.1.0/go.mod h1:qT0aEB35q79LLornSzeDH75LBf3aH1MV+jB5w9Wasec=
 github.com/moby/docker-image-spec v1.3.1 h1:jMKff3w6PgbfSa69GfNg+zN/XLhfXJGnEx3Nl2EsFP0=
@@ -198,8 +196,6 @@ github.com/opencontainers/image-spec v1.1.1 h1:y0fUlFfIZhPF1W537XOLg0/fcx6zcHCJw
 github.com/opencontainers/image-spec v1.1.1/go.mod h1:qpqAh3Dmcf36wStyyWU+kCeDgrGnAve2nCC8+7h8Q0M=
 github.com/orisano/pixelmatch v0.0.0-20220722002657-fb0b55479cde h1:x0TT0RDC7UhAVbbWWBzr41ElhJx5tXPWkIHA2HWPRuw=
 github.com/orisano/pixelmatch v0.0.0-20220722002657-fb0b55479cde/go.mod h1:nZgzbfBr3hhjoZnS66nKrHmduYNpc34ny7RK4z5/HM0=
-github.com/pierrec/lz4/v4 v4.1.25 h1:kocOqRffaIbU5djlIBr7Wh+cx82C0vtFb0fOurZHqD0=
-github.com/pierrec/lz4/v4 v4.1.25/go.mod h1:EoQMVJgeeEOMsCqCzqFm2O0cJvljX2nGZjcRIPL34O4=
 github.com/pierrec/lz4/v4 v4.1.26 h1:GrpZw1gZttORinvzBdXPUXATeqlJjqUG/D87TKMnhjY=
 github.com/pierrec/lz4/v4 v4.1.26/go.mod h1:EoQMVJgeeEOMsCqCzqFm2O0cJvljX2nGZjcRIPL34O4=
 github.com/pkg/errors v0.9.1 h1:FEBLx1zS214owpjy7qsBeixbURkuhQAwrK5UwLGTwt4=
@@ -214,8 +210,6 @@ github.com/prometheus/client_model v0.6.2 h1:oBsgwpGs7iVziMvrGhE53c/GrLUsZdHnqNw
 github.com/prometheus/client_model v0.6.2/go.mod h1:y3m2F6Gdpfy6Ut/GBsUqTWZqCUvMVzSfMLjcu6wAwpE=
 github.com/prometheus/common v0.67.5 h1:pIgK94WWlQt1WLwAC5j2ynLaBRDiinoAb86HZHTUGI4=
 github.com/prometheus/common v0.67.5/go.mod h1:SjE/0MzDEEAyrdr5Gqc6G+sXI67maCxzaT3A2+HqjUw=
-github.com/prometheus/procfs v0.19.2 h1:zUMhqEW66Ex7OXIiDkll3tl9a1ZdilUOd/F6ZXw4Vws=
-github.com/prometheus/procfs v0.19.2/go.mod h1:M0aotyiemPhBCM0z5w87kL22CxfcH05ZpYlu+b4J7mw=
 github.com/prometheus/procfs v0.20.1 h1:XwbrGOIplXW/AU3YhIhLODXMJYyC1isLFfYCsTEycfc=
 github.com/prometheus/procfs v0.20.1/go.mod h1:o9EMBZGRyvDrSPH1RqdxhojkuXstoe4UlK79eF5TGGo=
 github.com/rogpeppe/go-internal v1.14.1 h1:UQB4HGPB6osV0SQTLymcB4TgvyWu6ZyliaW0tI/otEQ=
@@ -265,30 +259,20 @@ github.com/yusufpapurcu/wmi v1.2.4 h1:zFUKzehAFReQwLys1b/iSMl+JQGSCSjtVqQn9bBrPo
 github.com/yusufpapurcu/wmi v1.2.4/go.mod h1:SBZ9tNy3G9/m5Oi98Zks0QjeHVDvuK0qfxQmPyzfmi0=
 go.opentelemetry.io/auto/sdk v1.2.1 h1:jXsnJ4Lmnqd11kwkBV2LgLoFMZKizbCi5fNZ/ipaZ64=
 go.opentelemetry.io/auto/sdk v1.2.1/go.mod h1:KRTj+aOaElaLi+wW1kO/DZRXwkF4C5xPbEe3ZiIhN7Y=
-go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp v0.65.0 h1:7iP2uCb7sGddAr30RRS6xjKy7AZ2JtTOPA3oolgVSw8=
-go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp v0.65.0/go.mod h1:c7hN3ddxs/z6q9xwvfLPk+UHlWRQyaeR1LdgfL/66l0=
 go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp v0.67.0 h1:OyrsyzuttWTSur2qN/Lm0m2a8yqyIjUVBZcxFPuXq2o=
 go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp v0.67.0/go.mod h1:C2NGBr+kAB4bk3xtMXfZ94gqFDtg/GkI7e9zqGh5Beg=
-go.opentelemetry.io/otel v1.41.0 h1:YlEwVsGAlCvczDILpUXpIpPSL/VPugt7zHThEMLce1c=
-go.opentelemetry.io/otel v1.41.0/go.mod h1:Yt4UwgEKeT05QbLwbyHXEwhnjxNO6D8L5PQP51/46dE=
 go.opentelemetry.io/otel v1.42.0 h1:lSQGzTgVR3+sgJDAU/7/ZMjN9Z+vUip7leaqBKy4sho=
 go.opentelemetry.io/otel v1.42.0/go.mod h1:lJNsdRMxCUIWuMlVJWzecSMuNjE7dOYyWlqOXWkdqCc=
 go.opentelemetry.io/otel/exporters/otlp/otlptrace v1.37.0 h1:Ahq7pZmv87yiyn3jeFz/LekZmPLLdKejuO3NcK9MssM=
 go.opentelemetry.io/otel/exporters/otlp/otlptrace v1.37.0/go.mod h1:MJTqhM0im3mRLw1i8uGHnCvUEeS7VwRyxlLC78PA18M=
 go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracehttp v1.41.0 h1:inYW9ZhgqiDqh6BioM7DVHHzEGVq76Db5897WLGZ5Go=
 go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracehttp v1.41.0/go.mod h1:Izur+Wt8gClgMJqO/cZ8wdeeMryJ/xxiOVgFSSfpDTY=
-go.opentelemetry.io/otel/metric v1.41.0 h1:rFnDcs4gRzBcsO9tS8LCpgR0dxg4aaxWlJxCno7JlTQ=
-go.opentelemetry.io/otel/metric v1.41.0/go.mod h1:xPvCwd9pU0VN8tPZYzDZV/BMj9CM9vs00GuBjeKhJps=
 go.opentelemetry.io/otel/metric v1.42.0 h1:2jXG+3oZLNXEPfNmnpxKDeZsFI5o4J+nz6xUlaFdF/4=
 go.opentelemetry.io/otel/metric v1.42.0/go.mod h1:RlUN/7vTU7Ao/diDkEpQpnz3/92J9ko05BIwxYa2SSI=
-go.opentelemetry.io/otel/sdk v1.41.0 h1:YPIEXKmiAwkGl3Gu1huk1aYWwtpRLeskpV+wPisxBp8=
-go.opentelemetry.io/otel/sdk v1.41.0/go.mod h1:ahFdU0G5y8IxglBf0QBJXgSe7agzjE4GiTJ6HT9ud90=
 go.opentelemetry.io/otel/sdk v1.42.0 h1:LyC8+jqk6UJwdrI/8VydAq/hvkFKNHZVIWuslJXYsDo=
-go.opentelemetry.io/otel/sdk/metric v1.40.0 h1:mtmdVqgQkeRxHgRv4qhyJduP3fYJRMX4AtAlbuWdCYw=
-go.opentelemetry.io/otel/sdk/metric v1.40.0/go.mod h1:4Z2bGMf0KSK3uRjlczMOeMhKU2rhUqdWNoKcYrtcBPg=
+go.opentelemetry.io/otel/sdk v1.42.0/go.mod h1:rGHCAxd9DAph0joO4W6OPwxjNTYWghRWmkHuGbayMts=
 go.opentelemetry.io/otel/sdk/metric v1.42.0 h1:D/1QR46Clz6ajyZ3G8SgNlTJKBdGp84q9RKCAZ3YGuA=
-go.opentelemetry.io/otel/trace v1.41.0 h1:Vbk2co6bhj8L59ZJ6/xFTskY+tGAbOnCtQGVVa9TIN0=
-go.opentelemetry.io/otel/trace v1.41.0/go.mod h1:U1NU4ULCoxeDKc09yCWdWe+3QoyweJcISEVa1RBzOis=
+go.opentelemetry.io/otel/sdk/metric v1.42.0/go.mod h1:Ua6AAlDKdZ7tdvaQKfSmnFTdHx37+J4ba8MwVCYM5hc=
 go.opentelemetry.io/otel/trace v1.42.0 h1:OUCgIPt+mzOnaUTpOQcBiM/PLQ/Op7oq6g4LenLmOYY=
 go.opentelemetry.io/otel/trace v1.42.0/go.mod h1:f3K9S+IFqnumBkKhRJMeaZeNk9epyhnCmQh/EysQCdc=
 go.opentelemetry.io/proto/otlp v1.7.1 h1:gTOMpGDb0WTBOP8JaO72iL3auEZhVmAQg4ipjOVAtj4=
@@ -299,8 +283,6 @@ go.uber.org/multierr v1.11.0 h1:blXXJkSxSSfBVBlC76pxqeO+LN3aDfLQo+309xJstO0=
 go.uber.org/multierr v1.11.0/go.mod h1:20+QtiLqy0Nd6FdQB9TLXag12DsQkrbs3htMFfDN80Y=
 go.uber.org/zap v1.27.1 h1:08RqriUEv8+ArZRYSTXy1LeBScaMpVSTBhCeaZYfMYc=
 go.uber.org/zap v1.27.1/go.mod h1:GB2qFLM7cTU87MWRP2mPIjqfIDnGu+VIO4V/SdhGo2E=
-go.yaml.in/yaml/v2 v2.4.3 h1:6gvOSjQoTB3vt1l+CU+tSyi/HOjfOjRLJ4YwYZGwRO0=
-go.yaml.in/yaml/v2 v2.4.3/go.mod h1:zSxWcmIDjOzPXpjlTTbAsKokqkDNAVtZO0WOMiT90s8=
 go.yaml.in/yaml/v2 v2.4.4 h1:tuyd0P+2Ont/d6e2rl3be67goVK4R6deVxCUX5vyPaQ=
 go.yaml.in/yaml/v2 v2.4.4/go.mod h1:gMZqIpDtDqOfM0uNfy0SkpRhvUryYH0Z6wdMYcacYXQ=
 go4.org v0.0.0-20260112195520-a5071408f32f h1:ziUVAjmTPwQMBmYR1tbdRFJPtTcQUI12fH9QQjfb0Sw=
@@ -322,8 +304,6 @@ golang.org/x/term v0.41.0 h1:QCgPso/Q3RTJx2Th4bDLqML4W6iJiaXFq2/ftQF13YU=
 golang.org/x/term v0.41.0/go.mod h1:3pfBgksrReYfZ5lvYM0kSO0LIkAl4Yl2bXOkKP7Ec2A=
 golang.org/x/text v0.35.0 h1:JOVx6vVDFokkpaq1AEptVzLTpDe9KGpj5tR4/X+ybL8=
 golang.org/x/text v0.35.0/go.mod h1:khi/HExzZJ2pGnjenulevKNX1W67CUy0AsXcNubPGCA=
-golang.org/x/time v0.14.0 h1:MRx4UaLrDotUKUdCIqzPC48t1Y9hANFKIRpNx+Te8PI=
-golang.org/x/time v0.14.0/go.mod h1:eL/Oa2bBBK0TkX57Fyni+NgnyQQN4LitPmob2Hjnqw4=
 golang.org/x/time v0.15.0 h1:bbrp8t3bGUeFOx08pvsMYRTCVSMk89u4tKbNOZbp88U=
 golang.org/x/time v0.15.0/go.mod h1:Y4YMaQmXwGQZoFaVFk4YpCt4FLQMYKZe9oeV/f4MSno=
 golang.org/x/xerrors v0.0.0-20191204190536-9bdfabe68543/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=

pkg/gotenberg/mocks.go

@@ -57,6 +57,8 @@ type PdfEngineMock struct {
 	EncryptMock        func(ctx context.Context, logger *zap.Logger, inputPath, userPassword, ownerPassword string) error
 	EmbedFilesMock     func(ctx context.Context, logger *zap.Logger, filePaths []string, inputPath string) error
 	WriteBookmarksMock func(ctx context.Context, logger *zap.Logger, inputPath string, bookmarks []Bookmark) error
+	WatermarkMock      func(ctx context.Context, logger *zap.Logger, inputPath string, stamp Stamp) error
+	StampMock          func(ctx context.Context, logger *zap.Logger, inputPath string, stamp Stamp) error
 }
 
 func (engine *PdfEngineMock) Merge(ctx context.Context, logger *zap.Logger, inputPaths []string, outputPath string) error {
@@ -103,6 +105,14 @@ func (engine *PdfEngineMock) WriteBookmarks(ctx context.Context, logger *zap.Log
 	return engine.WriteBookmarksMock(ctx, logger, inputPath, bookmarks)
 }
 
+func (engine *PdfEngineMock) Watermark(ctx context.Context, logger *zap.Logger, inputPath string, stamp Stamp) error {
+	return engine.WatermarkMock(ctx, logger, inputPath, stamp)
+}
+
+func (engine *PdfEngineMock) Stamp(ctx context.Context, logger *zap.Logger, inputPath string, stamp Stamp) error {
+	return engine.StampMock(ctx, logger, inputPath, stamp)
+}
+
 // PdfEngineProviderMock is a mock for the [PdfEngineProvider] interface.
 type PdfEngineProviderMock struct {
 	PdfEngineMock func() (PdfEngine, error)

pkg/gotenberg/pdfengine.go

@@ -28,6 +28,10 @@ var (
 	// ErrPdfEncryptionNotSupported is returned when encryption
 	// is not supported by the PDF engine.
 	ErrPdfEncryptionNotSupported = errors.New("encryption not supported")
+
+	// ErrPdfStampSourceNotSupported is returned when a stamp source type
+	// is not supported by the PDF engine.
+	ErrPdfStampSourceNotSupported = errors.New("stamp source not supported")
 )
 
 // PdfEngineInvalidArgsError represents an error returned by a PDF engine when
@@ -49,6 +53,33 @@ func NewPdfEngineInvalidArgs(engine, msg string) error {
 	return &PdfEngineInvalidArgsError{engine, msg}
 }
 
+const (
+	// StampSourceText represents a text-based stamp source.
+	StampSourceText string = "text"
+
+	// StampSourceImage represents an image-based stamp source.
+	StampSourceImage string = "image"
+
+	// StampSourcePDF represents a PDF-based stamp source.
+	StampSourcePDF string = "pdf"
+)
+
+// Stamp gathers the data required to apply a watermark or stamp to a PDF.
+type Stamp struct {
+	// Source is one of "text", "image", or "pdf".
+	Source string
+
+	// Expression is the text content (for text source) or file path (for
+	// image/pdf source).
+	Expression string
+
+	// Pages is the optional page range to apply the stamp to.
+	Pages string
+
+	// Options holds engine-specific styling options.
+	Options map[string]string
+}
+
 const (
 	// SplitModeIntervals represents a mode where a PDF is split at specific
 	// intervals.
@@ -166,6 +197,12 @@ type PdfEngine interface {
 	// without modifying the main PDF content.
 	// TODO: attachments instead? Rename the route?
 	EmbedFiles(ctx context.Context, logger *zap.Logger, filePaths []string, inputPath string) error
+
+	// Watermark applies a watermark (behind page content) to a PDF file.
+	Watermark(ctx context.Context, logger *zap.Logger, inputPath string, stamp Stamp) error
+
+	// Stamp applies a stamp (on top of page content) to a PDF file.
+	Stamp(ctx context.Context, logger *zap.Logger, inputPath string, stamp Stamp) error
 }
 
 // PdfEngineProvider offers an interface to instantiate a [PdfEngine].

pkg/modules/api/formdata.go

@@ -17,9 +17,15 @@ import (
 	"github.com/gotenberg/gotenberg/v8/pkg/gotenberg"
 )
 
-// EmbedsFormField represents the form field name for embedding files.
 const (
+	// EmbedsFormField represents the form field name for embedding files.
 	EmbedsFormField string = "embeds"
+
+	// WatermarksFormField represents the form field name for watermark files.
+	WatermarksFormField string = "watermarks"
+
+	// StampsFormField represents the form field name for stamp files.
+	StampsFormField string = "stamps"
 )
 
 // FormData is a helper for validating and hydrating values from a
@@ -406,17 +412,57 @@ func (form *FormData) MandatoryPaths(extensions []string, target *[]string) *For
 	return form
 }
 
+// Watermarks binds the absolute paths of form data files that should be
+// used as watermark sources. Only files uploaded with the "watermarks"
+// field name will be included.
+func (form *FormData) Watermarks(target *[]string) *FormData {
+	if form.errors != nil {
+		return form
+	}
+
+	if paths, ok := form.filesByField[WatermarksFormField]; ok {
+		*target = append(*target, paths...)
+	}
+
+	return form
+}
+
+// Stamps binds the absolute paths of form data files that should be
+// used as stamp sources. Only files uploaded with the "stamps"
+// field name will be included.
+func (form *FormData) Stamps(target *[]string) *FormData {
+	if form.errors != nil {
+		return form
+	}
+
+	if paths, ok := form.filesByField[StampsFormField]; ok {
+		*target = append(*target, paths...)
+	}
+
+	return form
+}
+
 // paths bind the absolute paths of form data files, according to a list of
 // file extensions, to a string slice variable.
-// embeds are excluded.
+// embeds, watermarks, and stamps are excluded.
 func (form *FormData) paths(extensions []string, target *[]string) *FormData {
 	embeds, ok := form.filesByField[EmbedsFormField]
+	watermarks, wmOk := form.filesByField[WatermarksFormField]
+	stamps, stOk := form.filesByField[StampsFormField]
 
 	for filename, path := range form.files {
 		if ok && slices.Contains(embeds, path) {
 			continue
 		}
 
+		if wmOk && slices.Contains(watermarks, path) {
+			continue
+		}
+
+		if stOk && slices.Contains(stamps, path) {
+			continue
+		}
+
 		for _, ext := range extensions {
 			// See https://github.com/gotenberg/gotenberg/issues/228.
 			if strings.ToLower(filepath.Ext(filename)) == ext {

pkg/modules/api/middlewares.go

@@ -61,6 +61,10 @@ func ParseError(err error) (int, string) {
 		return http.StatusBadRequest, "At least one PDF engine cannot process the requested metadata, while others may have failed to convert due to different issues"
 	}
 
+	if errors.Is(err, gotenberg.ErrPdfStampSourceNotSupported) {
+		return http.StatusBadRequest, "At least one PDF engine cannot process the requested stamp source type, while others may have failed due to different issues"
+	}
+
 	var invalidArgsError *gotenberg.PdfEngineInvalidArgsError
 	if errors.As(err, &invalidArgsError) {
 		return http.StatusBadRequest, invalidArgsError.Error()

pkg/modules/chromium/routes.go

@@ -415,6 +415,10 @@ func convertUrlRoute(chromium Api, engine gotenberg.PdfEngine) api.Route {
 			metadata := pdfengines.FormDataPdfMetadata(form, false)
 			userPassword, ownerPassword := pdfengines.FormDataPdfEncrypt(form)
 			embedPaths := pdfengines.FormDataPdfEmbeds(form)
+			watermark := pdfengines.FormDataPdfWatermark(form, false)
+			watermarkFiles := pdfengines.FormDataPdfWatermarkFiles(form)
+			stamp := pdfengines.FormDataPdfStamp(form, false)
+			stampFiles := pdfengines.FormDataPdfStampFiles(form)
 
 			var url string
 			err := form.
@@ -424,7 +428,14 @@ func convertUrlRoute(chromium Api, engine gotenberg.PdfEngine) api.Route {
 				return fmt.Errorf("validate form data: %w", err)
 			}
 
-			err = convertUrl(ctx, chromium, engine, url, options, mode, pdfFormats, metadata, userPassword, ownerPassword, embedPaths)
+			if (watermark.Source == gotenberg.StampSourceImage || watermark.Source == gotenberg.StampSourcePDF) && len(watermarkFiles) > 0 {
+				watermark.Expression = watermarkFiles[0]
+			}
+			if (stamp.Source == gotenberg.StampSourceImage || stamp.Source == gotenberg.StampSourcePDF) && len(stampFiles) > 0 {
+				stamp.Expression = stampFiles[0]
+			}
+
+			err = convertUrl(ctx, chromium, engine, url, options, mode, pdfFormats, metadata, userPassword, ownerPassword, embedPaths, watermark, stamp)
 			if err != nil {
 				return fmt.Errorf("convert URL to PDF: %w", err)
 			}
@@ -478,6 +489,10 @@ func convertHtmlRoute(chromium Api, engine gotenberg.PdfEngine) api.Route {
 			metadata := pdfengines.FormDataPdfMetadata(form, false)
 			userPassword, ownerPassword := pdfengines.FormDataPdfEncrypt(form)
 			embedPaths := pdfengines.FormDataPdfEmbeds(form)
+			watermark := pdfengines.FormDataPdfWatermark(form, false)
+			watermarkFiles := pdfengines.FormDataPdfWatermarkFiles(form)
+			stamp := pdfengines.FormDataPdfStamp(form, false)
+			stampFiles := pdfengines.FormDataPdfStampFiles(form)
 
 			var inputPath string
 			err := form.
@@ -487,8 +502,15 @@ func convertHtmlRoute(chromium Api, engine gotenberg.PdfEngine) api.Route {
 				return fmt.Errorf("validate form data: %w", err)
 			}
 
+			if (watermark.Source == gotenberg.StampSourceImage || watermark.Source == gotenberg.StampSourcePDF) && len(watermarkFiles) > 0 {
+				watermark.Expression = watermarkFiles[0]
+			}
+			if (stamp.Source == gotenberg.StampSourceImage || stamp.Source == gotenberg.StampSourcePDF) && len(stampFiles) > 0 {
+				stamp.Expression = stampFiles[0]
+			}
+
 			url := fmt.Sprintf("file://%s", inputPath)
-			err = convertUrl(ctx, chromium, engine, url, options, mode, pdfFormats, metadata, userPassword, ownerPassword, embedPaths)
+			err = convertUrl(ctx, chromium, engine, url, options, mode, pdfFormats, metadata, userPassword, ownerPassword, embedPaths, watermark, stamp)
 			if err != nil {
 				return fmt.Errorf("convert HTML to PDF: %w", err)
 			}
@@ -543,6 +565,10 @@ func convertMarkdownRoute(chromium Api, engine gotenberg.PdfEngine) api.Route {
 			metadata := pdfengines.FormDataPdfMetadata(form, false)
 			userPassword, ownerPassword := pdfengines.FormDataPdfEncrypt(form)
 			embedPaths := pdfengines.FormDataPdfEmbeds(form)
+			watermark := pdfengines.FormDataPdfWatermark(form, false)
+			watermarkFiles := pdfengines.FormDataPdfWatermarkFiles(form)
+			stamp := pdfengines.FormDataPdfStamp(form, false)
+			stampFiles := pdfengines.FormDataPdfStampFiles(form)
 
 			var (
 				inputPath     string
@@ -557,12 +583,19 @@ func convertMarkdownRoute(chromium Api, engine gotenberg.PdfEngine) api.Route {
 				return fmt.Errorf("validate form data: %w", err)
 			}
 
+			if (watermark.Source == gotenberg.StampSourceImage || watermark.Source == gotenberg.StampSourcePDF) && len(watermarkFiles) > 0 {
+				watermark.Expression = watermarkFiles[0]
+			}
+			if (stamp.Source == gotenberg.StampSourceImage || stamp.Source == gotenberg.StampSourcePDF) && len(stampFiles) > 0 {
+				stamp.Expression = stampFiles[0]
+			}
+
 			url, err := markdownToHtml(ctx, inputPath, markdownPaths)
 			if err != nil {
 				return fmt.Errorf("transform markdown file(s) to HTML: %w", err)
 			}
 
-			err = convertUrl(ctx, chromium, engine, url, options, mode, pdfFormats, metadata, userPassword, ownerPassword, embedPaths)
+			err = convertUrl(ctx, chromium, engine, url, options, mode, pdfFormats, metadata, userPassword, ownerPassword, embedPaths, watermark, stamp)
 			if err != nil {
 				return fmt.Errorf("convert markdown to PDF: %w", err)
 			}
@@ -686,7 +719,7 @@ func markdownToHtml(ctx *api.Context, inputPath string, markdownPaths []string)
 	return fmt.Sprintf("file://%s", inputPath), nil
 }
 
-func convertUrl(ctx *api.Context, chromium Api, engine gotenberg.PdfEngine, url string, options PdfOptions, mode gotenberg.SplitMode, pdfFormats gotenberg.PdfFormats, metadata map[string]any, userPassword, ownerPassword string, embedPaths []string) error {
+func convertUrl(ctx *api.Context, chromium Api, engine gotenberg.PdfEngine, url string, options PdfOptions, mode gotenberg.SplitMode, pdfFormats gotenberg.PdfFormats, metadata map[string]any, userPassword, ownerPassword string, embedPaths []string, watermark, stamp gotenberg.Stamp) error {
 	outputPath := ctx.GeneratePath(".pdf")
 	// See https://github.com/gotenberg/gotenberg/issues/1130.
 	filename := ctx.OutputFilename(outputPath)
@@ -758,6 +791,16 @@ func convertUrl(ctx *api.Context, chromium Api, engine gotenberg.PdfEngine, url
 		return fmt.Errorf("convert PDF(s): %w", err)
 	}
 
+	err = pdfengines.WatermarkStub(ctx, engine, watermark, convertOutputPaths)
+	if err != nil {
+		return fmt.Errorf("watermark PDFs: %w", err)
+	}
+
+	err = pdfengines.StampStub(ctx, engine, stamp, convertOutputPaths)
+	if err != nil {
+		return fmt.Errorf("stamp PDFs: %w", err)
+	}
+
 	err = pdfengines.EmbedFilesStub(ctx, engine, embedPaths, convertOutputPaths)
 	if err != nil {
 		return fmt.Errorf("embed files into PDFs: %w", err)

pkg/modules/exiftool/exiftool.go

@@ -254,6 +254,16 @@ func (engine *ExifTool) EmbedFiles(ctx context.Context, logger *zap.Logger, file
 	return fmt.Errorf("embed files with ExifTool: %w", gotenberg.ErrPdfEngineMethodNotSupported)
 }
 
+// Watermark is not available in this implementation.
+func (engine *ExifTool) Watermark(ctx context.Context, logger *zap.Logger, inputPath string, stamp gotenberg.Stamp) error {
+	return fmt.Errorf("watermark PDF with ExifTool: %w", gotenberg.ErrPdfEngineMethodNotSupported)
+}
+
+// Stamp is not available in this implementation.
+func (engine *ExifTool) Stamp(ctx context.Context, logger *zap.Logger, inputPath string, stamp gotenberg.Stamp) error {
+	return fmt.Errorf("stamp PDF with ExifTool: %w", gotenberg.ErrPdfEngineMethodNotSupported)
+}
+
 // Interface guards.
 var (
 	_ gotenberg.Module      = (*ExifTool)(nil)

pkg/modules/libreoffice/api/api.go

@@ -147,6 +147,29 @@ type Options struct {
 	// Possible values are: 75, 150, 300, 600 and 1200.
 	MaxImageResolution int
 
+	// NativeWatermarkText specifies the text for a watermark to be drawn on
+	// every page of the exported PDF file.
+	// See https://help.libreoffice.org/latest/en-US/text/shared/guide/pdf_params.html.
+	NativeWatermarkText string
+
+	// NativeWatermarkColor specifies the color for the watermark text as a
+	// decimal long value. Default is 8388223 (light green).
+	NativeWatermarkColor int
+
+	// NativeWatermarkFontHeight specifies the font size for the watermark text.
+	NativeWatermarkFontHeight int
+
+	// NativeWatermarkRotateAngle specifies the rotation angle for the watermark
+	// text in tenths of a degree (e.g., 450 = 45°).
+	NativeWatermarkRotateAngle int
+
+	// NativeWatermarkFontName specifies the font name for the watermark text.
+	// Default is "Helvetica".
+	NativeWatermarkFontName string
+
+	// NativeTiledWatermarkText specifies the tiled watermark text.
+	NativeTiledWatermarkText string
+
 	// PdfFormats allows to convert the resulting PDF to PDF/A-1b, PDF/A-2b,
 	// PDF/A-3b and PDF/UA.
 	PdfFormats gotenberg.PdfFormats
@@ -178,6 +201,12 @@ func DefaultOptions() Options {
 		Quality:                         90,
 		ReduceImageResolution:           false,
 		MaxImageResolution:              300,
+		NativeWatermarkText:             "",
+		NativeWatermarkColor:            8388223,
+		NativeWatermarkFontHeight:       0,
+		NativeWatermarkRotateAngle:      0,
+		NativeWatermarkFontName:         "Helvetica",
+		NativeTiledWatermarkText:        "",
 		PdfFormats: gotenberg.PdfFormats{
 			PdfA:  "",
 			PdfUa: false,

pkg/modules/libreoffice/api/libreoffice.go

@@ -302,6 +302,30 @@ func (p *libreOfficeProcess) pdf(ctx context.Context, logger *zap.Logger, inputP
 	args = append(args, "--export", fmt.Sprintf("ReduceImageResolution=%t", options.ReduceImageResolution))
 	args = append(args, "--export", fmt.Sprintf("MaxImageResolution=%d", options.MaxImageResolution))
 
+	if options.NativeWatermarkText != "" {
+		args = append(args, "--export", fmt.Sprintf("Watermark=%s", options.NativeWatermarkText))
+	}
+
+	if options.NativeWatermarkColor != 0 {
+		args = append(args, "--export", fmt.Sprintf("WatermarkColor=%d", options.NativeWatermarkColor))
+	}
+
+	if options.NativeWatermarkFontHeight > 0 {
+		args = append(args, "--export", fmt.Sprintf("WatermarkFontHeight=%d", options.NativeWatermarkFontHeight))
+	}
+
+	if options.NativeWatermarkRotateAngle != 0 {
+		args = append(args, "--export", fmt.Sprintf("WatermarkRotateAngle=%d", options.NativeWatermarkRotateAngle))
+	}
+
+	if options.NativeWatermarkFontName != "" && options.NativeWatermarkFontName != "Helvetica" {
+		args = append(args, "--export", fmt.Sprintf("WatermarkFontName=%s", options.NativeWatermarkFontName))
+	}
+
+	if options.NativeTiledWatermarkText != "" {
+		args = append(args, "--export", fmt.Sprintf("TiledWatermark=%s", options.NativeTiledWatermarkText))
+	}
+
 	switch options.PdfFormats.PdfA {
 	case "":
 	case gotenberg.PdfA1b:

pkg/modules/libreoffice/pdfengine/pdfengine.go

@@ -116,6 +116,16 @@ func (engine *LibreOfficePdfEngine) EmbedFiles(ctx context.Context, logger *zap.
 	return fmt.Errorf("embed files with LibreOffice: %w", gotenberg.ErrPdfEngineMethodNotSupported)
 }
 
+// Watermark is not available in this implementation.
+func (engine *LibreOfficePdfEngine) Watermark(ctx context.Context, logger *zap.Logger, inputPath string, stamp gotenberg.Stamp) error {
+	return fmt.Errorf("watermark PDF with LibreOffice: %w", gotenberg.ErrPdfEngineMethodNotSupported)
+}
+
+// Stamp is not available in this implementation.
+func (engine *LibreOfficePdfEngine) Stamp(ctx context.Context, logger *zap.Logger, inputPath string, stamp gotenberg.Stamp) error {
+	return fmt.Errorf("stamp PDF with LibreOffice: %w", gotenberg.ErrPdfEngineMethodNotSupported)
+}
+
 // Interface guards.
 var (
 	_ gotenberg.Module      = (*LibreOfficePdfEngine)(nil)

pkg/modules/libreoffice/routes.go

@@ -32,6 +32,10 @@ func convertRoute(libreOffice libreofficeapi.Uno, engine gotenberg.PdfEngine) ap
 			metadata := pdfengines.FormDataPdfMetadata(form, false)
 			userPassword, ownerPassword := pdfengines.FormDataPdfEncrypt(form)
 			embedPaths := pdfengines.FormDataPdfEmbeds(form)
+			watermark := pdfengines.FormDataPdfWatermark(form, false)
+			watermarkFiles := pdfengines.FormDataPdfWatermarkFiles(form)
+			stamp := pdfengines.FormDataPdfStamp(form, false)
+			stampFiles := pdfengines.FormDataPdfStampFiles(form)
 
 			zeroValuedSplitMode := gotenberg.SplitMode{}
 
@@ -60,6 +64,12 @@ func convertRoute(libreOffice libreofficeapi.Uno, engine gotenberg.PdfEngine) ap
 				quality                         int
 				reduceImageResolution           bool
 				maxImageResolution              int
+				nativeWatermarkText             string
+				nativeWatermarkColor            int
+				nativeWatermarkFontHeight       int
+				nativeWatermarkRotateAngle      int
+				nativeWatermarkFontName         string
+				nativeTiledWatermarkText        string
 				nativePdfFormats                bool
 				merge                           bool
 				flatten                         bool
@@ -128,6 +138,48 @@ func convertRoute(libreOffice libreofficeapi.Uno, engine gotenberg.PdfEngine) ap
 					maxImageResolution = intValue
 					return nil
 				}).
+				String("nativeWatermarkText", &nativeWatermarkText, defaultOptions.NativeWatermarkText).
+				Custom("nativeWatermarkColor", func(value string) error {
+					if value == "" {
+						nativeWatermarkColor = defaultOptions.NativeWatermarkColor
+						return nil
+					}
+					intValue, err := strconv.Atoi(value)
+					if err != nil {
+						return err
+					}
+					nativeWatermarkColor = intValue
+					return nil
+				}).
+				Custom("nativeWatermarkFontHeight", func(value string) error {
+					if value == "" {
+						nativeWatermarkFontHeight = defaultOptions.NativeWatermarkFontHeight
+						return nil
+					}
+					intValue, err := strconv.Atoi(value)
+					if err != nil {
+						return err
+					}
+					if intValue < 0 {
+						return errors.New("value is inferior to 0")
+					}
+					nativeWatermarkFontHeight = intValue
+					return nil
+				}).
+				Custom("nativeWatermarkRotateAngle", func(value string) error {
+					if value == "" {
+						nativeWatermarkRotateAngle = defaultOptions.NativeWatermarkRotateAngle
+						return nil
+					}
+					intValue, err := strconv.Atoi(value)
+					if err != nil {
+						return err
+					}
+					nativeWatermarkRotateAngle = intValue
+					return nil
+				}).
+				String("nativeWatermarkFontName", &nativeWatermarkFontName, defaultOptions.NativeWatermarkFontName).
+				String("nativeTiledWatermarkText", &nativeTiledWatermarkText, defaultOptions.NativeTiledWatermarkText).
 				Bool("nativePdfFormats", &nativePdfFormats, true).
 				Bool("merge", &merge, false).
 				Bool("flatten", &flatten, false).
@@ -136,6 +188,13 @@ func convertRoute(libreOffice libreofficeapi.Uno, engine gotenberg.PdfEngine) ap
 				return fmt.Errorf("validate form data: %w", err)
 			}
 
+			if (watermark.Source == gotenberg.StampSourceImage || watermark.Source == gotenberg.StampSourcePDF) && len(watermarkFiles) > 0 {
+				watermark.Expression = watermarkFiles[0]
+			}
+			if (stamp.Source == gotenberg.StampSourceImage || stamp.Source == gotenberg.StampSourcePDF) && len(stampFiles) > 0 {
+				stamp.Expression = stampFiles[0]
+			}
+
 			outputPaths := make([]string, len(inputPaths))
 			for i, inputPath := range inputPaths {
 				outputPaths[i] = ctx.GeneratePath(".pdf")
@@ -163,6 +222,12 @@ func convertRoute(libreOffice libreofficeapi.Uno, engine gotenberg.PdfEngine) ap
 					Quality:                         quality,
 					ReduceImageResolution:           reduceImageResolution,
 					MaxImageResolution:              maxImageResolution,
+					NativeWatermarkText:             nativeWatermarkText,
+					NativeWatermarkColor:            nativeWatermarkColor,
+					NativeWatermarkFontHeight:       nativeWatermarkFontHeight,
+					NativeWatermarkRotateAngle:      nativeWatermarkRotateAngle,
+					NativeWatermarkFontName:         nativeWatermarkFontName,
+					NativeTiledWatermarkText:        nativeTiledWatermarkText,
 				}
 
 				if nativePdfFormats && splitMode == zeroValuedSplitMode {
@@ -253,6 +318,16 @@ func convertRoute(libreOffice libreofficeapi.Uno, engine gotenberg.PdfEngine) ap
 				}
 			}
 
+			err = pdfengines.WatermarkStub(ctx, engine, watermark, outputPaths)
+			if err != nil {
+				return fmt.Errorf("watermark PDFs: %w", err)
+			}
+
+			err = pdfengines.StampStub(ctx, engine, stamp, outputPaths)
+			if err != nil {
+				return fmt.Errorf("stamp PDFs: %w", err)
+			}
+
 			err = pdfengines.EmbedFilesStub(ctx, engine, embedPaths, outputPaths)
 			if err != nil {
 				return fmt.Errorf("embed files into PDFs: %w", err)

pkg/modules/pdfcpu/pdfcpu.go

@@ -379,6 +379,57 @@ func (engine *PdfCpu) Encrypt(ctx context.Context, logger *zap.Logger, inputPath
 	return nil
 }
 
+// Watermark applies a watermark (behind page content) to a PDF file using pdfcpu.
+func (engine *PdfCpu) Watermark(ctx context.Context, logger *zap.Logger, inputPath string, stamp gotenberg.Stamp) error {
+	return engine.applyStampOrWatermark(ctx, logger, "watermark", inputPath, stamp)
+}
+
+// Stamp applies a stamp (on top of page content) to a PDF file using pdfcpu.
+func (engine *PdfCpu) Stamp(ctx context.Context, logger *zap.Logger, inputPath string, stamp gotenberg.Stamp) error {
+	return engine.applyStampOrWatermark(ctx, logger, "stamp", inputPath, stamp)
+}
+
+func (engine *PdfCpu) applyStampOrWatermark(ctx context.Context, logger *zap.Logger, command string, inputPath string, stamp gotenberg.Stamp) error {
+	var mode string
+	switch stamp.Source {
+	case gotenberg.StampSourceText:
+		mode = "text"
+	case gotenberg.StampSourceImage:
+		mode = "image"
+	case gotenberg.StampSourcePDF:
+		mode = "pdf"
+	default:
+		return fmt.Errorf("%s PDF with pdfcpu: %w", command, gotenberg.ErrPdfStampSourceNotSupported)
+	}
+
+	// Build description from Options map.
+	var descParts []string
+	for k, v := range stamp.Options {
+		descParts = append(descParts, fmt.Sprintf("%s:%s", k, v))
+	}
+	description := strings.Join(descParts, ", ")
+
+	args := []string{command, "add", "-mode", mode}
+
+	if stamp.Pages != "" {
+		args = append(args, "-pages", stamp.Pages)
+	}
+
+	args = append(args, "--", stamp.Expression, description, inputPath, inputPath)
+
+	cmd, err := gotenberg.CommandContext(ctx, logger, engine.binPath, args...)
+	if err != nil {
+		return fmt.Errorf("create command: %w", err)
+	}
+
+	_, err = cmd.Exec()
+	if err != nil {
+		return fmt.Errorf("%s PDF with pdfcpu: %w", command, err)
+	}
+
+	return nil
+}
+
 // Interface guards.
 var (
 	_ gotenberg.Module      = (*PdfCpu)(nil)

pkg/modules/pdfengines/multi.go

@@ -22,6 +22,8 @@ type multiPdfEngines struct {
 	embedEngines          []gotenberg.PdfEngine
 	readBookmarksEngines  []gotenberg.PdfEngine
 	writeBookmarksEngines []gotenberg.PdfEngine
+	watermarkEngines      []gotenberg.PdfEngine
+	stampEngines          []gotenberg.PdfEngine
 }
 
 func newMultiPdfEngines(
@@ -34,7 +36,9 @@ func newMultiPdfEngines(
 	passwordEngines,
 	embedEngines,
 	readBookmarksEngines,
-	writeBookmarksEngines []gotenberg.PdfEngine,
+	writeBookmarksEngines,
+	watermarkEngines,
+	stampEngines []gotenberg.PdfEngine,
 ) *multiPdfEngines {
 	return &multiPdfEngines{
 		mergeEngines:          mergeEngines,
@@ -47,6 +51,8 @@ func newMultiPdfEngines(
 		embedEngines:          embedEngines,
 		readBookmarksEngines:  readBookmarksEngines,
 		writeBookmarksEngines: writeBookmarksEngines,
+		watermarkEngines:      watermarkEngines,
+		stampEngines:          stampEngines,
 	}
 }
 
@@ -369,6 +375,56 @@ func (multi *multiPdfEngines) EmbedFiles(ctx context.Context, logger *zap.Logger
 	return fmt.Errorf("embed files into PDF using multi PDF engines: %w", err)
 }
 
+// Watermark applies a watermark (behind page content) to a PDF file using the
+// first available engine that supports watermarking.
+func (multi *multiPdfEngines) Watermark(ctx context.Context, logger *zap.Logger, inputPath string, stamp gotenberg.Stamp) error {
+	var err error
+	errChan := make(chan error, 1)
+
+	for _, engine := range multi.watermarkEngines {
+		go func(engine gotenberg.PdfEngine) {
+			errChan <- engine.Watermark(ctx, logger, inputPath, stamp)
+		}(engine)
+
+		select {
+		case watermarkErr := <-errChan:
+			errored := multierr.AppendInto(&err, watermarkErr)
+			if !errored {
+				return nil
+			}
+		case <-ctx.Done():
+			return ctx.Err()
+		}
+	}
+
+	return fmt.Errorf("watermark PDF with multi PDF engines: %w", err)
+}
+
+// Stamp applies a stamp (on top of page content) to a PDF file using the
+// first available engine that supports stamping.
+func (multi *multiPdfEngines) Stamp(ctx context.Context, logger *zap.Logger, inputPath string, stamp gotenberg.Stamp) error {
+	var err error
+	errChan := make(chan error, 1)
+
+	for _, engine := range multi.stampEngines {
+		go func(engine gotenberg.PdfEngine) {
+			errChan <- engine.Stamp(ctx, logger, inputPath, stamp)
+		}(engine)
+
+		select {
+		case stampErr := <-errChan:
+			errored := multierr.AppendInto(&err, stampErr)
+			if !errored {
+				return nil
+			}
+		case <-ctx.Done():
+			return ctx.Err()
+		}
+	}
+
+	return fmt.Errorf("stamp PDF with multi PDF engines: %w", err)
+}
+
 // Interface guards.
 var (
 	_ gotenberg.PdfEngine = (*multiPdfEngines)(nil)

pkg/modules/pdfengines/pdfengines.go

@@ -38,6 +38,8 @@ type PdfEngines struct {
 	embedNames          []string
 	readBookmarksNames  []string
 	writeBookmarksNames []string
+	watermarkNames      []string
+	stampNames          []string
 	engines             []gotenberg.PdfEngine
 	disableRoutes       bool
 }
@@ -58,6 +60,8 @@ func (mod *PdfEngines) Descriptor() gotenberg.ModuleDescriptor {
 			fs.StringSlice("pdfengines-embed-engines", []string{"pdfcpu"}, "Set the PDF engines and their order for the file embedding feature - empty means all")
 			fs.StringSlice("pdfengines-read-bookmarks-engines", []string{"pdfcpu"}, "Set the PDF engines and their order for the read bookmarks feature - empty means all")
 			fs.StringSlice("pdfengines-write-bookmarks-engines", []string{"pdfcpu"}, "Set the PDF engines and their order for the write bookmarks feature - empty means all")
+			fs.StringSlice("pdfengines-watermark-engines", []string{"pdfcpu", "pdftk"}, "Set the PDF engines and their order for the watermark feature - empty means all")
+			fs.StringSlice("pdfengines-stamp-engines", []string{"pdfcpu", "pdftk"}, "Set the PDF engines and their order for the stamp feature - empty means all")
 			fs.Bool("pdfengines-disable-routes", false, "Disable the routes")
 
 			// Deprecated flags.
@@ -87,6 +91,8 @@ func (mod *PdfEngines) Provision(ctx *gotenberg.Context) error {
 	embedNames := flags.MustStringSlice("pdfengines-embed-engines")
 	readBookmarksNames := flags.MustStringSlice("pdfengines-read-bookmarks-engines")
 	writeBookmarksNames := flags.MustStringSlice("pdfengines-write-bookmarks-engines")
+	watermarkNames := flags.MustStringSlice("pdfengines-watermark-engines")
+	stampNames := flags.MustStringSlice("pdfengines-stamp-engines")
 	mod.disableRoutes = flags.MustBool("pdfengines-disable-routes")
 
 	engines, err := ctx.Modules(new(gotenberg.PdfEngine))
@@ -163,6 +169,16 @@ func (mod *PdfEngines) Provision(ctx *gotenberg.Context) error {
 		mod.writeBookmarksNames = writeBookmarksNames
 	}
 
+	mod.watermarkNames = defaultNames
+	if len(watermarkNames) > 0 {
+		mod.watermarkNames = watermarkNames
+	}
+
+	mod.stampNames = defaultNames
+	if len(stampNames) > 0 {
+		mod.stampNames = stampNames
+	}
+
 	return nil
 }
 
@@ -214,6 +230,8 @@ func (mod *PdfEngines) Validate() error {
 	findNonExistingEngines(mod.embedNames)
 	findNonExistingEngines(mod.readBookmarksNames)
 	findNonExistingEngines(mod.writeBookmarksNames)
+	findNonExistingEngines(mod.watermarkNames)
+	findNonExistingEngines(mod.stampNames)
 
 	if len(nonExistingEngines) == 0 {
 		return nil
@@ -236,6 +254,8 @@ func (mod *PdfEngines) SystemMessages() []string {
 		fmt.Sprintf("embed engines - %s", strings.Join(mod.embedNames[:], " ")),
 		fmt.Sprintf("read bookmarks engines - %s", strings.Join(mod.readBookmarksNames[:], " ")),
 		fmt.Sprintf("write bookmarks engines - %s", strings.Join(mod.writeBookmarksNames[:], " ")),
+		fmt.Sprintf("watermark engines - %s", strings.Join(mod.watermarkNames[:], " ")),
+		fmt.Sprintf("stamp engines - %s", strings.Join(mod.stampNames[:], " ")),
 	}
 }
 
@@ -266,6 +286,8 @@ func (mod *PdfEngines) PdfEngine() (gotenberg.PdfEngine, error) {
 		engines(mod.embedNames),
 		engines(mod.readBookmarksNames),
 		engines(mod.writeBookmarksNames),
+		engines(mod.watermarkNames),
+		engines(mod.stampNames),
 	), nil
 }
 
@@ -293,6 +315,8 @@ func (mod *PdfEngines) Routes() ([]api.Route, error) {
 		writeBookmarksRoute(engine),
 		encryptRoute(engine),
 		embedRoute(engine),
+		watermarkRoute(engine),
+		stampRoute(engine),
 	}, nil
 }
 

pkg/modules/pdfengines/routes.go

@@ -391,6 +391,122 @@ func EmbedFilesStub(ctx *api.Context, engine gotenberg.PdfEngine, embedPaths []s
 	return nil
 }
 
+// FormDataPdfWatermark creates a [gotenberg.Stamp] for watermarking from the
+// form data.
+func FormDataPdfWatermark(form *api.FormData, mandatory bool) gotenberg.Stamp {
+	return formDataPdfStampOrWatermark(form, "watermark", mandatory)
+}
+
+// FormDataPdfStamp creates a [gotenberg.Stamp] for stamping from the form data.
+func FormDataPdfStamp(form *api.FormData, mandatory bool) gotenberg.Stamp {
+	return formDataPdfStampOrWatermark(form, "stamp", mandatory)
+}
+
+func formDataPdfStampOrWatermark(form *api.FormData, prefix string, mandatory bool) gotenberg.Stamp {
+	var (
+		source     string
+		expression string
+		pages      string
+		options    map[string]string
+	)
+
+	sourceFunc := func(value string) error {
+		if value != "" && value != gotenberg.StampSourceText && value != gotenberg.StampSourceImage && value != gotenberg.StampSourcePDF {
+			return fmt.Errorf("wrong value, expected either '%s', '%s' or '%s'", gotenberg.StampSourceText, gotenberg.StampSourceImage, gotenberg.StampSourcePDF)
+		}
+		source = value
+		return nil
+	}
+
+	optionsFunc := func(value string) error {
+		if value == "" {
+			return nil
+		}
+		err := json.Unmarshal([]byte(value), &options)
+		if err != nil {
+			return fmt.Errorf("unmarshal %s options: %w", prefix, err)
+		}
+		return nil
+	}
+
+	if mandatory {
+		form.
+			MandatoryCustom(prefix+"Source", func(value string) error {
+				return sourceFunc(value)
+			}).
+			String(prefix+"Expression", &expression, "").
+			String(prefix+"Pages", &pages, "").
+			Custom(prefix+"Options", func(value string) error {
+				return optionsFunc(value)
+			})
+	} else {
+		form.
+			Custom(prefix+"Source", func(value string) error {
+				return sourceFunc(value)
+			}).
+			String(prefix+"Expression", &expression, "").
+			String(prefix+"Pages", &pages, "").
+			Custom(prefix+"Options", func(value string) error {
+				return optionsFunc(value)
+			})
+	}
+
+	return gotenberg.Stamp{
+		Source:     source,
+		Expression: expression,
+		Pages:      pages,
+		Options:    options,
+	}
+}
+
+// FormDataPdfWatermarkFiles extracts watermark file paths from form data.
+func FormDataPdfWatermarkFiles(form *api.FormData) []string {
+	var paths []string
+	form.Watermarks(&paths)
+	return paths
+}
+
+// FormDataPdfStampFiles extracts stamp file paths from form data.
+func FormDataPdfStampFiles(form *api.FormData) []string {
+	var paths []string
+	form.Stamps(&paths)
+	return paths
+}
+
+// WatermarkStub applies a watermark to a list of PDF files. If the stamp has
+// no source, it does nothing.
+func WatermarkStub(ctx *api.Context, engine gotenberg.PdfEngine, stamp gotenberg.Stamp, inputPaths []string) error {
+	if stamp.Source == "" {
+		return nil
+	}
+
+	for _, inputPath := range inputPaths {
+		err := engine.Watermark(ctx, ctx.Log(), inputPath, stamp)
+		if err != nil {
+			return fmt.Errorf("watermark '%s': %w", inputPath, err)
+		}
+	}
+
+	return nil
+}
+
+// StampStub applies a stamp to a list of PDF files. If the stamp has
+// no source, it does nothing.
+func StampStub(ctx *api.Context, engine gotenberg.PdfEngine, stamp gotenberg.Stamp, inputPaths []string) error {
+	if stamp.Source == "" {
+		return nil
+	}
+
+	for _, inputPath := range inputPaths {
+		err := engine.Stamp(ctx, ctx.Log(), inputPath, stamp)
+		if err != nil {
+			return fmt.Errorf("stamp '%s': %w", inputPath, err)
+		}
+	}
+
+	return nil
+}
+
 // mergeRoute returns an [api.Route] which can merge PDFs.
 func mergeRoute(engine gotenberg.PdfEngine) api.Route {
 	return api.Route{
@@ -406,6 +522,10 @@ func mergeRoute(engine gotenberg.PdfEngine) api.Route {
 			bookmarks := FormDataPdfBookmarks(form, false)
 			userPassword, ownerPassword := FormDataPdfEncrypt(form)
 			embedPaths := FormDataPdfEmbeds(form)
+			watermark := FormDataPdfWatermark(form, false)
+			watermarkFiles := FormDataPdfWatermarkFiles(form)
+			stamp := FormDataPdfStamp(form, false)
+			stampFiles := FormDataPdfStampFiles(form)
 
 			var inputPaths []string
 			var flatten bool
@@ -419,6 +539,13 @@ func mergeRoute(engine gotenberg.PdfEngine) api.Route {
 				return fmt.Errorf("validate form data: %w", err)
 			}
 
+			if (watermark.Source == gotenberg.StampSourceImage || watermark.Source == gotenberg.StampSourcePDF) && len(watermarkFiles) > 0 {
+				watermark.Expression = watermarkFiles[0]
+			}
+			if (stamp.Source == gotenberg.StampSourceImage || stamp.Source == gotenberg.StampSourcePDF) && len(stampFiles) > 0 {
+				stamp.Expression = stampFiles[0]
+			}
+
 			outputPath := ctx.GeneratePath(".pdf")
 			err = engine.Merge(ctx, ctx.Log(), inputPaths, outputPath)
 			if err != nil {
@@ -430,6 +557,16 @@ func mergeRoute(engine gotenberg.PdfEngine) api.Route {
 				return fmt.Errorf("convert PDF: %w", err)
 			}
 
+			err = WatermarkStub(ctx, engine, watermark, outputPaths)
+			if err != nil {
+				return fmt.Errorf("watermark PDFs: %w", err)
+			}
+
+			err = StampStub(ctx, engine, stamp, outputPaths)
+			if err != nil {
+				return fmt.Errorf("stamp PDFs: %w", err)
+			}
+
 			err = EmbedFilesStub(ctx, engine, embedPaths, outputPaths)
 			if err != nil {
 				return fmt.Errorf("embed files into PDFs: %w", err)
@@ -520,6 +657,10 @@ func splitRoute(engine gotenberg.PdfEngine) api.Route {
 			metadata := FormDataPdfMetadata(form, false)
 			userPassword, ownerPassword := FormDataPdfEncrypt(form)
 			embedPaths := FormDataPdfEmbeds(form)
+			watermark := FormDataPdfWatermark(form, false)
+			watermarkFiles := FormDataPdfWatermarkFiles(form)
+			stamp := FormDataPdfStamp(form, false)
+			stampFiles := FormDataPdfStampFiles(form)
 
 			var inputPaths []string
 			var flatten bool
@@ -531,6 +672,13 @@ func splitRoute(engine gotenberg.PdfEngine) api.Route {
 				return fmt.Errorf("validate form data: %w", err)
 			}
 
+			if (watermark.Source == gotenberg.StampSourceImage || watermark.Source == gotenberg.StampSourcePDF) && len(watermarkFiles) > 0 {
+				watermark.Expression = watermarkFiles[0]
+			}
+			if (stamp.Source == gotenberg.StampSourceImage || stamp.Source == gotenberg.StampSourcePDF) && len(stampFiles) > 0 {
+				stamp.Expression = stampFiles[0]
+			}
+
 			outputPaths, err := SplitPdfStub(ctx, engine, mode, inputPaths)
 			if err != nil {
 				return fmt.Errorf("split PDFs: %w", err)
@@ -541,6 +689,16 @@ func splitRoute(engine gotenberg.PdfEngine) api.Route {
 				return fmt.Errorf("convert PDFs: %w", err)
 			}
 
+			err = WatermarkStub(ctx, engine, watermark, convertOutputPaths)
+			if err != nil {
+				return fmt.Errorf("watermark PDFs: %w", err)
+			}
+
+			err = StampStub(ctx, engine, stamp, convertOutputPaths)
+			if err != nil {
+				return fmt.Errorf("stamp PDFs: %w", err)
+			}
+
 			err = EmbedFilesStub(ctx, engine, embedPaths, convertOutputPaths)
 			if err != nil {
 				return fmt.Errorf("embed files into PDFs: %w", err)
@@ -904,3 +1062,105 @@ func embedRoute(engine gotenberg.PdfEngine) api.Route {
 		},
 	}
 }
+
+// watermarkRoute returns an [api.Route] which can add watermarks to PDFs.
+//
+//nolint:dupl
+func watermarkRoute(engine gotenberg.PdfEngine) api.Route {
+	return api.Route{
+		Method:      http.MethodPost,
+		Path:        "/forms/pdfengines/watermark",
+		IsMultipart: true,
+		Handler: func(c echo.Context) error {
+			ctx := c.Get("context").(*api.Context)
+
+			form := ctx.FormData()
+			stamp := FormDataPdfWatermark(form, true)
+			watermarkFiles := FormDataPdfWatermarkFiles(form)
+
+			var inputPaths []string
+			err := form.
+				MandatoryPaths([]string{".pdf"}, &inputPaths).
+				Validate()
+			if err != nil {
+				return fmt.Errorf("validate form data: %w", err)
+			}
+
+			if stamp.Source == gotenberg.StampSourceImage || stamp.Source == gotenberg.StampSourcePDF {
+				if len(watermarkFiles) == 0 {
+					return api.WrapError(
+						errors.New("no watermark file provided"),
+						api.NewSentinelHttpError(
+							http.StatusBadRequest,
+							"Invalid form data: a watermark file is required for image or pdf source",
+						),
+					)
+				}
+				stamp.Expression = watermarkFiles[0]
+			}
+
+			err = WatermarkStub(ctx, engine, stamp, inputPaths)
+			if err != nil {
+				return fmt.Errorf("watermark PDFs: %w", err)
+			}
+
+			err = ctx.AddOutputPaths(inputPaths...)
+			if err != nil {
+				return fmt.Errorf("add output paths: %w", err)
+			}
+
+			return nil
+		},
+	}
+}
+
+// stampRoute returns an [api.Route] which can add stamps to PDFs.
+//
+//nolint:dupl
+func stampRoute(engine gotenberg.PdfEngine) api.Route {
+	return api.Route{
+		Method:      http.MethodPost,
+		Path:        "/forms/pdfengines/stamp",
+		IsMultipart: true,
+		Handler: func(c echo.Context) error {
+			ctx := c.Get("context").(*api.Context)
+
+			form := ctx.FormData()
+			stamp := FormDataPdfStamp(form, true)
+			stampFiles := FormDataPdfStampFiles(form)
+
+			var inputPaths []string
+			err := form.
+				MandatoryPaths([]string{".pdf"}, &inputPaths).
+				Validate()
+			if err != nil {
+				return fmt.Errorf("validate form data: %w", err)
+			}
+
+			if stamp.Source == gotenberg.StampSourceImage || stamp.Source == gotenberg.StampSourcePDF {
+				if len(stampFiles) == 0 {
+					return api.WrapError(
+						errors.New("no stamp file provided"),
+						api.NewSentinelHttpError(
+							http.StatusBadRequest,
+							"Invalid form data: a stamp file is required for image or pdf source",
+						),
+					)
+				}
+				stamp.Expression = stampFiles[0]
+			}
+
+			err = StampStub(ctx, engine, stamp, inputPaths)
+			if err != nil {
+				return fmt.Errorf("stamp PDFs: %w", err)
+			}
+
+			err = ctx.AddOutputPaths(inputPaths...)
+			if err != nil {
+				return fmt.Errorf("add output paths: %w", err)
+			}
+
+			return nil
+		},
+	}
+}

pkg/modules/pdftk/pdftk.go

@@ -203,6 +203,64 @@ func (engine *PdfTk) EmbedFiles(ctx context.Context, logger *zap.Logger, filePat
 	return fmt.Errorf("embed files with PDFtk: %w", gotenberg.ErrPdfEngineMethodNotSupported)
 }
 
+// Watermark applies a watermark (behind page content) to a PDF file using PDFtk.
+// Only PDF source is supported.
+func (engine *PdfTk) Watermark(ctx context.Context, logger *zap.Logger, inputPath string, stamp gotenberg.Stamp) error {
+	if stamp.Source != gotenberg.StampSourcePDF {
+		return fmt.Errorf("watermark PDF with PDFtk: %w", gotenberg.ErrPdfStampSourceNotSupported)
+	}
+
+	tmpPath := inputPath + ".tmp"
+
+	args := []string{inputPath, "background", stamp.Expression, "output", tmpPath}
+
+	cmd, err := gotenberg.CommandContext(ctx, logger, engine.binPath, args...)
+	if err != nil {
+		return fmt.Errorf("create command: %w", err)
+	}
+
+	_, err = cmd.Exec()
+	if err != nil {
+		return fmt.Errorf("watermark PDF with PDFtk: %w", err)
+	}
+
+	err = os.Rename(tmpPath, inputPath)
+	if err != nil {
+		return fmt.Errorf("rename temporary output file with input file: %w", err)
+	}
+
+	return nil
+}
+
+// Stamp applies a stamp (on top of page content) to a PDF file using PDFtk.
+// Only PDF source is supported.
+func (engine *PdfTk) Stamp(ctx context.Context, logger *zap.Logger, inputPath string, stamp gotenberg.Stamp) error {
+	if stamp.Source != gotenberg.StampSourcePDF {
+		return fmt.Errorf("stamp PDF with PDFtk: %w", gotenberg.ErrPdfStampSourceNotSupported)
+	}
+
+	tmpPath := inputPath + ".tmp"
+
+	args := []string{inputPath, "stamp", stamp.Expression, "output", tmpPath}
+
+	cmd, err := gotenberg.CommandContext(ctx, logger, engine.binPath, args...)
+	if err != nil {
+		return fmt.Errorf("create command: %w", err)
+	}
+
+	_, err = cmd.Exec()
+	if err != nil {
+		return fmt.Errorf("stamp PDF with PDFtk: %w", err)
+	}
+
+	err = os.Rename(tmpPath, inputPath)
+	if err != nil {
+		return fmt.Errorf("rename temporary output file with input file: %w", err)
+	}
+
+	return nil
+}
+
 // Interface guards.
 var (
 	_ gotenberg.Module      = (*PdfTk)(nil)

pkg/modules/qpdf/qpdf.go

@@ -221,6 +221,16 @@ func (engine *QPdf) EmbedFiles(ctx context.Context, logger *zap.Logger, filePath
 	return fmt.Errorf("embed files with QPDF: %w", gotenberg.ErrPdfEngineMethodNotSupported)
 }
 
+// Watermark is not available in this implementation.
+func (engine *QPdf) Watermark(ctx context.Context, logger *zap.Logger, inputPath string, stamp gotenberg.Stamp) error {
+	return fmt.Errorf("watermark PDF with QPDF: %w", gotenberg.ErrPdfEngineMethodNotSupported)
+}
+
+// Stamp is not available in this implementation.
+func (engine *QPdf) Stamp(ctx context.Context, logger *zap.Logger, inputPath string, stamp gotenberg.Stamp) error {
+	return fmt.Errorf("stamp PDF with QPDF: %w", gotenberg.ErrPdfEngineMethodNotSupported)
+}
+
 var (
 	_ gotenberg.Module      = (*QPdf)(nil)
 	_ gotenberg.Provisioner = (*QPdf)(nil)

test/integration/features/chromium_convert_html.feature

@@ -988,6 +988,28 @@ Feature: /forms/chromium/convert/html
     Then there should be 1 PDF(s) in the response
     Then the response PDF(s) should be encrypted
 
+  @watermark
+  Scenario: POST /forms/chromium/convert/html (Watermark - Text)
+    Given I have a default Gotenberg container
+    When I make a "POST" request to Gotenberg at the "/forms/chromium/convert/html" endpoint with the following form data and header(s):
+      | files               | testdata/page-1-html/index.html | file  |
+      | watermarkSource     | text                            | field |
+      | watermarkExpression | CONFIDENTIAL                    | field |
+    Then the response status code should be 200
+    Then the response header "Content-Type" should be "application/pdf"
+    Then there should be 1 PDF(s) in the response
+
+  @stamp
+  Scenario: POST /forms/chromium/convert/html (Stamp - Text)
+    Given I have a default Gotenberg container
+    When I make a "POST" request to Gotenberg at the "/forms/chromium/convert/html" endpoint with the following form data and header(s):
+      | files           | testdata/page-1-html/index.html | file  |
+      | stampSource     | text                            | field |
+      | stampExpression | DRAFT                           | field |
+    Then the response status code should be 200
+    Then the response header "Content-Type" should be "application/pdf"
+    Then there should be 1 PDF(s) in the response
+
   @embed
   Scenario: POST /forms/chromium/convert/html (Embeds)
     Given I have a default Gotenberg container
@@ -1007,9 +1029,11 @@ Feature: /forms/chromium/convert/html
   # FIXME: once decrypt is done, add encrypt and check after the content of the PDF.
   @convert
   @metadata
+  @watermark
+  @stamp
   @flatten
   @embed
-  Scenario: POST /forms/chromium/convert/html (PDF/A-1b & PDF/UA-1 & Metadata & Flatten & Embeds)
+  Scenario: POST /forms/chromium/convert/html (PDF/A-1b & PDF/UA-1 & Metadata & Watermark & Stamp & Flatten & Embeds)
     Given I have a default Gotenberg container
     When I make a "POST" request to Gotenberg at the "/forms/chromium/convert/html" endpoint with the following form data and header(s):
       | files                     | testdata/page-1-html/index.html                                                                                                                                                                                                                                                                           | file   |
@@ -1025,7 +1049,7 @@ Feature: /forms/chromium/convert/html
     Then there should be 1 PDF(s) in the response
     Then there should be the following file(s) in the response:
       | foo.pdf |
-    Then the response PDF(s) should be valid "PDF/A-1b" with a tolerance of 9 failed rule(s)
+    Then the response PDF(s) should be valid "PDF/A-1b" with a tolerance of 11 failed rule(s)
     Then the response PDF(s) should be valid "PDF/UA-1" with a tolerance of 2 failed rule(s)
     Then the response PDF(s) should be flatten
     Then the response PDF(s) should have the "embed_1.xml" file embedded

test/integration/features/libreoffice_convert.feature

@@ -563,6 +563,62 @@ Feature: /forms/libreoffice/convert
     Then there should be 1 PDF(s) in the response
     Then the response PDF(s) should be encrypted
 
+  @watermark
+  Scenario: POST /forms/libreoffice/convert (Watermark - Text)
+    Given I have a default Gotenberg container
+    When I make a "POST" request to Gotenberg at the "/forms/libreoffice/convert" endpoint with the following form data and header(s):
+      | files               | testdata/page_1.docx | file  |
+      | watermarkSource     | text                 | field |
+      | watermarkExpression | CONFIDENTIAL         | field |
+    Then the response status code should be 200
+    Then the response header "Content-Type" should be "application/pdf"
+    Then there should be 1 PDF(s) in the response
+
+  @stamp
+  Scenario: POST /forms/libreoffice/convert (Stamp - Text)
+    Given I have a default Gotenberg container
+    When I make a "POST" request to Gotenberg at the "/forms/libreoffice/convert" endpoint with the following form data and header(s):
+      | files           | testdata/page_1.docx | file  |
+      | stampSource     | text                 | field |
+      | stampExpression | DRAFT                | field |
+    Then the response status code should be 200
+    Then the response header "Content-Type" should be "application/pdf"
+    Then there should be 1 PDF(s) in the response
+
+  @watermark
+  Scenario: POST /forms/libreoffice/convert (Native Watermark - Text)
+    Given I have a default Gotenberg container
+    When I make a "POST" request to Gotenberg at the "/forms/libreoffice/convert" endpoint with the following form data and header(s):
+      | files               | testdata/page_1.docx | file  |
+      | nativeWatermarkText | CONFIDENTIAL         | field |
+    Then the response status code should be 200
+    Then the response header "Content-Type" should be "application/pdf"
+    Then there should be 1 PDF(s) in the response
+
+  @watermark
+  Scenario: POST /forms/libreoffice/convert (Native Watermark - Text with Options)
+    Given I have a default Gotenberg container
+    When I make a "POST" request to Gotenberg at the "/forms/libreoffice/convert" endpoint with the following form data and header(s):
+      | files                      | testdata/page_1.docx | file  |
+      | nativeWatermarkText        | DRAFT                | field |
+      | nativeWatermarkColor       | 16711680             | field |
+      | nativeWatermarkFontHeight  | 48                   | field |
+      | nativeWatermarkRotateAngle | 450                  | field |
+      | nativeWatermarkFontName    | Courier              | field |
+    Then the response status code should be 200
+    Then the response header "Content-Type" should be "application/pdf"
+    Then there should be 1 PDF(s) in the response
+
+  @watermark
+  Scenario: POST /forms/libreoffice/convert (Native Watermark - Tiled)
+    Given I have a default Gotenberg container
+    When I make a "POST" request to Gotenberg at the "/forms/libreoffice/convert" endpoint with the following form data and header(s):
+      | files                    | testdata/page_1.docx | file  |
+      | nativeTiledWatermarkText | CONFIDENTIAL         | field |
+    Then the response status code should be 200
+    Then the response header "Content-Type" should be "application/pdf"
+    Then there should be 1 PDF(s) in the response
+
   @embed
   Scenario: POST /forms/libreoffice/convert (Embeds)
     Given I have a default Gotenberg container
@@ -582,15 +638,21 @@ Feature: /forms/libreoffice/convert
   # FIXME: once decrypt is done, add encrypt and check after the content of the PDF.
   @convert
   @metadata
+  @watermark
+  @stamp
   @flatten
   @embed
-  Scenario: POST /forms/libreoffice/convert (PDF/A-1b & PDF/UA-1 & Metadata & Flatten & Embeds)
+  Scenario: POST /forms/libreoffice/convert (PDF/A-1b & PDF/UA-1 & Metadata & Watermark & Stamp & Flatten & Embeds)
     Given I have a default Gotenberg container
     When I make a "POST" request to Gotenberg at the "/forms/libreoffice/convert" endpoint with the following form data and header(s):
       | files                     | testdata/page_1.docx                                                                                                                                                                                                                                                                                      | file   |
       | pdfa                      | PDF/A-1b                                                                                                                                                                                                                                                                                                  | field  |
       | pdfua                     | true                                                                                                                                                                                                                                                                                                      | field  |
       | metadata                  | {"Author":"Julien Neuhart","Copyright":"Julien Neuhart","CreateDate":"2006-09-18T16:27:50-04:00","Creator":"Gotenberg","Keywords":["first","second"],"Marked":true,"ModDate":"2006-09-18T16:27:50-04:00","PDFVersion":1.7,"Producer":"Gotenberg","Subject":"Sample","Title":"Sample","Trapped":"Unknown"} | field  |
+      | watermarkSource           | text                                                                                                                                                                                                                                                                                                      | field  |
+      | watermarkExpression       | CONFIDENTIAL                                                                                                                                                                                                                                                                                              | field  |
+      | stampSource               | text                                                                                                                                                                                                                                                                                                      | field  |
+      | stampExpression           | DRAFT                                                                                                                                                                                                                                                                                                     | field  |
       | flatten                   | true                                                                                                                                                                                                                                                                                                      | field  |
       | embeds                    | testdata/embed_1.xml                                                                                                                                                                                                                                                                                      | file   |
       | embeds                    | testdata/embed_2.xml                                                                                                                                                                                                                                                                                      | file   |
@@ -600,8 +662,8 @@ Feature: /forms/libreoffice/convert
     Then there should be 1 PDF(s) in the response
     Then there should be the following file(s) in the response:
       | foo.pdf |
-    Then the response PDF(s) should be valid "PDF/A-1b" with a tolerance of 10 failed rule(s)
-    Then the response PDF(s) should be valid "PDF/UA-1" with a tolerance of 2 failed rule(s)
+    Then the response PDF(s) should be valid "PDF/A-1b" with a tolerance of 12 failed rule(s)
+    Then the response PDF(s) should be valid "PDF/UA-1" with a tolerance of 5 failed rule(s)
     Then the response PDF(s) should be flatten
     Then the response PDF(s) should have the "embed_1.xml" file embedded
     Then the response PDF(s) should have the "embed_2.xml" file embedded

test/integration/features/pdfengines_merge.feature

@@ -401,6 +401,30 @@ Feature: /forms/pdfengines/merge
     Then there should be 1 PDF(s) in the response
     Then the response PDF(s) should be encrypted
 
+  @watermark
+  Scenario: POST /forms/pdfengines/merge (Watermark - Text)
+    Given I have a default Gotenberg container
+    When I make a "POST" request to Gotenberg at the "/forms/pdfengines/merge" endpoint with the following form data and header(s):
+      | files               | testdata/page_1.pdf | file  |
+      | files               | testdata/page_2.pdf | file  |
+      | watermarkSource     | text                | field |
+      | watermarkExpression | CONFIDENTIAL        | field |
+    Then the response status code should be 200
+    Then the response header "Content-Type" should be "application/pdf"
+    Then there should be 1 PDF(s) in the response
+
+  @stamp
+  Scenario: POST /forms/pdfengines/merge (Stamp - Text)
+    Given I have a default Gotenberg container
+    When I make a "POST" request to Gotenberg at the "/forms/pdfengines/merge" endpoint with the following form data and header(s):
+      | files           | testdata/page_1.pdf | file  |
+      | files           | testdata/page_2.pdf | file  |
+      | stampSource     | text                | field |
+      | stampExpression | DRAFT               | field |
+    Then the response status code should be 200
+    Then the response header "Content-Type" should be "application/pdf"
+    Then there should be 1 PDF(s) in the response
+
   @embed
   Scenario: POST /foo/forms/pdfengines/merge (Embeds)
     Given I have a default Gotenberg container
@@ -417,10 +441,12 @@ Feature: /forms/pdfengines/merge
   # FIXME: once decrypt is done, add encrypt and check after the content of the PDF.
   @convert
   @metadata
+  @watermark
+  @stamp
   @flatten
   @embed
   @bookmarks
-  Scenario: POST /forms/pdfengines/merge (PDF/A-1b & PDF/UA-1 & Metadata & Flatten & Embeds & Bookmarks)
+  Scenario: POST /forms/pdfengines/merge (PDF/A-1b & PDF/UA-1 & Metadata & Watermark & Stamp & Flatten & Embeds & Bookmarks)
     Given I have a default Gotenberg container
     When I make a "POST" request to Gotenberg at the "/forms/pdfengines/merge" endpoint with the following form data and header(s):
       | files                     | testdata/page_1.pdf                                                                                                                                                                                                                                                                                       | file   |
@@ -428,6 +454,10 @@ Feature: /forms/pdfengines/merge
       | pdfa                      | PDF/A-1b                                                                                                                                                                                                                                                                                                  | field  |
       | pdfua                     | true                                                                                                                                                                                                                                                                                                      | field  |
       | metadata                  | {"Author":"Julien Neuhart","Copyright":"Julien Neuhart","CreateDate":"2006-09-18T16:27:50-04:00","Creator":"Gotenberg","Keywords":["first","second"],"Marked":true,"ModDate":"2006-09-18T16:27:50-04:00","PDFVersion":1.7,"Producer":"Gotenberg","Subject":"Sample","Title":"Sample","Trapped":"Unknown"} | field  |
+      | watermarkSource           | text                                                                                                                                                                                                                                                                                                      | field  |
+      | watermarkExpression       | CONFIDENTIAL                                                                                                                                                                                                                                                                                              | field  |
+      | stampSource               | text                                                                                                                                                                                                                                                                                                      | field  |
+      | stampExpression           | DRAFT                                                                                                                                                                                                                                                                                                     | field  |
       | bookmarks                 | [{"title":"Merged Index","page":1}]                                                                                                                                                                                                                                                                       | field  |
       | flatten                   | true                                                                                                                                                                                                                                                                                                      | field  |
       | embeds                    | testdata/embed_1.xml                                                                                                                                                                                                                                                                                      | file   |
@@ -447,8 +477,8 @@ Feature: /forms/pdfengines/merge
       """
       Page 2
       """
-    Then the response PDF(s) should be valid "PDF/A-1b" with a tolerance of 10 failed rule(s)
-    Then the response PDF(s) should be valid "PDF/UA-1" with a tolerance of 2 failed rule(s)
+    Then the response PDF(s) should be valid "PDF/A-1b" with a tolerance of 12 failed rule(s)
+    Then the response PDF(s) should be valid "PDF/UA-1" with a tolerance of 5 failed rule(s)
     Then the response PDF(s) should be flatten
     Then the response PDF(s) should have the "embed_1.xml" file embedded
     Then the response PDF(s) should have the "embed_2.xml" file embedded

test/integration/features/pdfengines_split.feature

@@ -473,6 +473,32 @@ Feature: /forms/pdfengines/split
     Then there should be 2 PDF(s) in the response
     Then the response PDF(s) should be encrypted
 
+  @watermark
+  Scenario: POST /forms/pdfengines/split (Watermark - Text)
+    Given I have a default Gotenberg container
+    When I make a "POST" request to Gotenberg at the "/forms/pdfengines/split" endpoint with the following form data and header(s):
+      | files               | testdata/pages_3.pdf | file  |
+      | splitMode           | intervals            | field |
+      | splitSpan           | 2                    | field |
+      | watermarkSource     | text                 | field |
+      | watermarkExpression | CONFIDENTIAL         | field |
+    Then the response status code should be 200
+    Then the response header "Content-Type" should be "application/zip"
+    Then there should be 2 PDF(s) in the response
+
+  @stamp
+  Scenario: POST /forms/pdfengines/split (Stamp - Text)
+    Given I have a default Gotenberg container
+    When I make a "POST" request to Gotenberg at the "/forms/pdfengines/split" endpoint with the following form data and header(s):
+      | files           | testdata/pages_3.pdf | file  |
+      | splitMode       | intervals            | field |
+      | splitSpan       | 2                    | field |
+      | stampSource     | text                 | field |
+      | stampExpression | DRAFT                | field |
+    Then the response status code should be 200
+    Then the response header "Content-Type" should be "application/zip"
+    Then there should be 2 PDF(s) in the response
+
   @embed
   Scenario: POST /foo/forms/pdfengines/split (Embeds)
     Given I have a default Gotenberg container
@@ -494,20 +520,26 @@ Feature: /forms/pdfengines/split
   # FIXME: once decrypt is done, add encrypt and check after the content of the PDFs.
   @convert
   @metadata
+  @watermark
+  @stamp
   @flatten
   @embed
-  Scenario: POST /forms/pdfengines/split (PDF/A-1b & PDF/UA-1 & Metadata & Flatten & Embeds)
+  Scenario: POST /forms/pdfengines/split (PDF/A-1b & PDF/UA-1 & Metadata & Watermark & Stamp & Flatten & Embeds)
     Given I have a default Gotenberg container
     When I make a "POST" request to Gotenberg at the "/forms/pdfengines/split" endpoint with the following form data and header(s):
-      | files     | testdata/pages_3.pdf                                                                                                                                                                                                                                                                                      | file  |
-      | splitMode | intervals                                                                                                                                                                                                                                                                                                 | field |
-      | splitSpan | 2                                                                                                                                                                                                                                                                                                         | field |
-      | pdfa      | PDF/A-1b                                                                                                                                                                                                                                                                                                  | field |
-      | pdfua     | true                                                                                                                                                                                                                                                                                                      | field |
-      | metadata  | {"Author":"Julien Neuhart","Copyright":"Julien Neuhart","CreateDate":"2006-09-18T16:27:50-04:00","Creator":"Gotenberg","Keywords":["first","second"],"Marked":true,"ModDate":"2006-09-18T16:27:50-04:00","PDFVersion":1.7,"Producer":"Gotenberg","Subject":"Sample","Title":"Sample","Trapped":"Unknown"} | field |
-      | flatten   | true                                                                                                                                                                                                                                                                                                      | field |
-      | embeds    | testdata/embed_1.xml                                                                                                                                                                                                                                                                                      | file  |
-      | embeds    | testdata/embed_2.xml                                                                                                                                                                                                                                                                                      | file  |
+      | files               | testdata/pages_3.pdf                                                                                                                                                                                                                                                                                      | file  |
+      | splitMode           | intervals                                                                                                                                                                                                                                                                                                 | field |
+      | splitSpan           | 2                                                                                                                                                                                                                                                                                                         | field |
+      | pdfa                | PDF/A-1b                                                                                                                                                                                                                                                                                                  | field |
+      | pdfua               | true                                                                                                                                                                                                                                                                                                      | field |
+      | metadata            | {"Author":"Julien Neuhart","Copyright":"Julien Neuhart","CreateDate":"2006-09-18T16:27:50-04:00","Creator":"Gotenberg","Keywords":["first","second"],"Marked":true,"ModDate":"2006-09-18T16:27:50-04:00","PDFVersion":1.7,"Producer":"Gotenberg","Subject":"Sample","Title":"Sample","Trapped":"Unknown"} | field |
+      | watermarkSource     | text                                                                                                                                                                                                                                                                                                      | field |
+      | watermarkExpression | CONFIDENTIAL                                                                                                                                                                                                                                                                                              | field |
+      | stampSource         | text                                                                                                                                                                                                                                                                                                      | field |
+      | stampExpression     | DRAFT                                                                                                                                                                                                                                                                                                     | field |
+      | flatten             | true                                                                                                                                                                                                                                                                                                      | field |
+      | embeds              | testdata/embed_1.xml                                                                                                                                                                                                                                                                                      | file  |
+      | embeds              | testdata/embed_2.xml                                                                                                                                                                                                                                                                                      | file  |
     Then the response status code should be 200
     Then the response header "Content-Type" should be "application/zip"
     Then there should be 2 PDF(s) in the response
@@ -528,8 +560,8 @@ Feature: /forms/pdfengines/split
       """
       Page 3
       """
-    Then the response PDF(s) should be valid "PDF/A-1b" with a tolerance of 10 failed rule(s)
-    Then the response PDF(s) should be valid "PDF/UA-1" with a tolerance of 2 failed rule(s)
+    Then the response PDF(s) should be valid "PDF/A-1b" with a tolerance of 12 failed rule(s)
+    Then the response PDF(s) should be valid "PDF/UA-1" with a tolerance of 5 failed rule(s)
     Then the response PDF(s) should be flatten
     Then the response PDF(s) should have the "embed_1.xml" file embedded
     Then the response PDF(s) should have the "embed_2.xml" file embedded

test/integration/features/pdfengines_stamp.feature

@@ -0,0 +1,211 @@
+@pdfengines
+@pdfengines-stamp
+@stamp
+Feature: /forms/pdfengines/stamp
+
+  Scenario: POST /forms/pdfengines/stamp (Text - pdfcpu)
+    Given I have a Gotenberg container with the following environment variable(s):
+      | PDFENGINES_STAMP_ENGINES | pdfcpu |
+    When I make a "POST" request to Gotenberg at the "/forms/pdfengines/stamp" endpoint with the following form data and header(s):
+      | files           | testdata/page_1.pdf | file  |
+      | stampSource     | text                | field |
+      | stampExpression | CONFIDENTIAL        | field |
+    Then the response status code should be 200
+    Then the response header "Content-Type" should be "application/pdf"
+    Then there should be 1 PDF(s) in the response
+    Then the "page_1.pdf" PDF should have 1 page(s)
+
+  Scenario: POST /forms/pdfengines/stamp (Text with Pages - pdfcpu)
+    Given I have a Gotenberg container with the following environment variable(s):
+      | PDFENGINES_STAMP_ENGINES | pdfcpu |
+    When I make a "POST" request to Gotenberg at the "/forms/pdfengines/stamp" endpoint with the following form data and header(s):
+      | files           | testdata/pages_3.pdf | file  |
+      | stampSource     | text                 | field |
+      | stampExpression | DRAFT                | field |
+      | stampPages      | 1-2                  | field |
+    Then the response status code should be 200
+    Then the response header "Content-Type" should be "application/pdf"
+    Then there should be 1 PDF(s) in the response
+    Then the "pages_3.pdf" PDF should have 3 page(s)
+
+  Scenario: POST /forms/pdfengines/stamp (Text with Options - pdfcpu)
+    Given I have a Gotenberg container with the following environment variable(s):
+      | PDFENGINES_STAMP_ENGINES | pdfcpu |
+    When I make a "POST" request to Gotenberg at the "/forms/pdfengines/stamp" endpoint with the following form data and header(s):
+      | files           | testdata/page_1.pdf                                  | file  |
+      | stampSource     | text                                                 | field |
+      | stampExpression | SAMPLE                                               | field |
+      | stampOptions    | {"scale":"0.5 abs","rot":"45","fillcolor":"#FF0000"} | field |
+    Then the response status code should be 200
+    Then the response header "Content-Type" should be "application/pdf"
+    Then there should be 1 PDF(s) in the response
+
+  Scenario: POST /forms/pdfengines/stamp (Image - pdfcpu)
+    Given I have a Gotenberg container with the following environment variable(s):
+      | PDFENGINES_STAMP_ENGINES | pdfcpu |
+    When I make a "POST" request to Gotenberg at the "/forms/pdfengines/stamp" endpoint with the following form data and header(s):
+      | files       | testdata/page_1.pdf    | file  |
+      | stamps      | testdata/watermark.png | file  |
+      | stampSource | image                  | field |
+    Then the response status code should be 200
+    Then the response header "Content-Type" should be "application/pdf"
+    Then there should be 1 PDF(s) in the response
+
+  Scenario: POST /forms/pdfengines/stamp (PDF - pdfcpu)
+    Given I have a Gotenberg container with the following environment variable(s):
+      | PDFENGINES_STAMP_ENGINES | pdfcpu |
+    When I make a "POST" request to Gotenberg at the "/forms/pdfengines/stamp" endpoint with the following form data and header(s):
+      | files       | testdata/page_1.pdf | file  |
+      | stamps      | testdata/page_2.pdf | file  |
+      | stampSource | pdf                 | field |
+    Then the response status code should be 200
+    Then the response header "Content-Type" should be "application/pdf"
+    Then there should be 1 PDF(s) in the response
+
+  Scenario: POST /forms/pdfengines/stamp (PDF - pdftk)
+    Given I have a Gotenberg container with the following environment variable(s):
+      | PDFENGINES_STAMP_ENGINES | pdftk |
+    When I make a "POST" request to Gotenberg at the "/forms/pdfengines/stamp" endpoint with the following form data and header(s):
+      | files       | testdata/page_1.pdf | file  |
+      | stamps      | testdata/page_2.pdf | file  |
+      | stampSource | pdf                 | field |
+    Then the response status code should be 200
+    Then the response header "Content-Type" should be "application/pdf"
+    Then there should be 1 PDF(s) in the response
+
+  Scenario: POST /forms/pdfengines/stamp (Text - pdftk unsupported)
+    Given I have a Gotenberg container with the following environment variable(s):
+      | PDFENGINES_STAMP_ENGINES | pdftk |
+    When I make a "POST" request to Gotenberg at the "/forms/pdfengines/stamp" endpoint with the following form data and header(s):
+      | files           | testdata/page_1.pdf | file  |
+      | stampSource     | text                | field |
+      | stampExpression | CONFIDENTIAL        | field |
+    Then the response status code should be 400
+    Then the response body should match string:
+      """
+      At least one PDF engine cannot process the requested stamp source type, while others may have failed due to different issues
+      """
+
+  Scenario: POST /forms/pdfengines/stamp (Many PDFs)
+    Given I have a default Gotenberg container
+    When I make a "POST" request to Gotenberg at the "/forms/pdfengines/stamp" endpoint with the following form data and header(s):
+      | files           | testdata/page_1.pdf | file  |
+      | files           | testdata/page_2.pdf | file  |
+      | stampSource     | text                | field |
+      | stampExpression | DRAFT               | field |
+    Then the response status code should be 200
+    Then the response header "Content-Type" should be "application/zip"
+    Then there should be 2 PDF(s) in the response
+
+  Scenario: POST /forms/pdfengines/stamp (Bad Request - No Source)
+    Given I have a default Gotenberg container
+    When I make a "POST" request to Gotenberg at the "/forms/pdfengines/stamp" endpoint with the following form data and header(s):
+      | files | testdata/page_1.pdf | file |
+    Then the response status code should be 400
+    Then the response body should match string:
+      """
+      Invalid form data: form field 'stampSource' is required
+      """
+
+  Scenario: POST /forms/pdfengines/stamp (Bad Request - Invalid Source)
+    Given I have a default Gotenberg container
+    When I make a "POST" request to Gotenberg at the "/forms/pdfengines/stamp" endpoint with the following form data and header(s):
+      | files       | testdata/page_1.pdf | file  |
+      | stampSource | foo                 | field |
+    Then the response status code should be 400
+    Then the response body should contain string:
+      """
+      Invalid form data: form field 'stampSource' is invalid
+      """
+
+  Scenario: POST /forms/pdfengines/stamp (Bad Request - Missing File for Image Source)
+    Given I have a default Gotenberg container
+    When I make a "POST" request to Gotenberg at the "/forms/pdfengines/stamp" endpoint with the following form data and header(s):
+      | files       | testdata/page_1.pdf | file  |
+      | stampSource | image               | field |
+    Then the response status code should be 400
+    Then the response body should match string:
+      """
+      Invalid form data: a stamp file is required for image or pdf source
+      """
+
+  Scenario: POST /forms/pdfengines/stamp (Bad Request - Missing File for PDF Source)
+    Given I have a default Gotenberg container
+    When I make a "POST" request to Gotenberg at the "/forms/pdfengines/stamp" endpoint with the following form data and header(s):
+      | files       | testdata/page_1.pdf | file  |
+      | stampSource | pdf                 | field |
+    Then the response status code should be 400
+    Then the response body should match string:
+      """
+      Invalid form data: a stamp file is required for image or pdf source
+      """
+
+  Scenario: POST /forms/pdfengines/stamp (Bad Request - No PDF)
+    Given I have a default Gotenberg container
+    When I make a "POST" request to Gotenberg at the "/forms/pdfengines/stamp" endpoint with the following form data and header(s):
+      | stampSource     | text         | field |
+      | stampExpression | CONFIDENTIAL | field |
+    Then the response status code should be 400
+    Then the response body should match string:
+      """
+      Invalid form data: no form file found for extensions: [.pdf]
+      """
+
+  Scenario: POST /forms/pdfengines/stamp (Routes Disabled)
+    Given I have a Gotenberg container with the following environment variable(s):
+      | PDFENGINES_DISABLE_ROUTES | true |
+    When I make a "POST" request to Gotenberg at the "/forms/pdfengines/stamp" endpoint with the following form data and header(s):
+      | files           | testdata/page_1.pdf | file  |
+      | stampSource     | text                | field |
+      | stampExpression | CONFIDENTIAL        | field |
+    Then the response status code should be 404
+
+  Scenario: POST /forms/pdfengines/stamp (Gotenberg Trace)
+    Given I have a default Gotenberg container
+    When I make a "POST" request to Gotenberg at the "/forms/pdfengines/stamp" endpoint with the following form data and header(s):
+      | files           | testdata/page_1.pdf    | file   |
+      | stampSource     | text                   | field  |
+      | stampExpression | CONFIDENTIAL           | field  |
+      | Gotenberg-Trace | forms_pdfengines_stamp | header |
+    Then the response status code should be 200
+    Then the response header "Content-Type" should be "application/pdf"
+    Then the response header "Gotenberg-Trace" should be "forms_pdfengines_stamp"
+    Then the Gotenberg container should log the following entries:
+      | "trace":"forms_pdfengines_stamp" |
+
+  @webhook
+  Scenario: POST /forms/pdfengines/stamp (Webhook)
+    Given I have a default Gotenberg container
+    Given I have a webhook server
+    When I make a "POST" request to Gotenberg at the "/forms/pdfengines/stamp" endpoint with the following form data and header(s):
+      | files                       | testdata/page_1.pdf                          | file   |
+      | stampSource                 | text                                         | field  |
+      | stampExpression             | CONFIDENTIAL                                 | field  |
+      | Gotenberg-Webhook-Url       | http://host.docker.internal:%d/webhook       | header |
+      | Gotenberg-Webhook-Error-Url | http://host.docker.internal:%d/webhook/error | header |
+    Then the response status code should be 204
+    When I wait for the asynchronous request to the webhook
+    Then the webhook request header "Content-Type" should be "application/pdf"
+    Then there should be 1 PDF(s) in the webhook request
+
+  Scenario: POST /forms/pdfengines/stamp (Basic Auth)
+    Given I have a Gotenberg container with the following environment variable(s):
+      | API_ENABLE_BASIC_AUTH             | true |
+      | GOTENBERG_API_BASIC_AUTH_USERNAME | foo  |
+      | GOTENBERG_API_BASIC_AUTH_PASSWORD | bar  |
+    When I make a "POST" request to Gotenberg at the "/forms/pdfengines/stamp" endpoint with the following form data and header(s):
+      | files           | testdata/page_1.pdf | file  |
+      | stampSource     | text                | field |
+      | stampExpression | CONFIDENTIAL        | field |
+    Then the response status code should be 401
+
+  Scenario: POST /foo/forms/pdfengines/stamp (Root Path)
+    Given I have a Gotenberg container with the following environment variable(s):
+      | API_ENABLE_DEBUG_ROUTE | true  |
+      | API_ROOT_PATH          | /foo/ |
+    When I make a "POST" request to Gotenberg at the "/foo/forms/pdfengines/stamp" endpoint with the following form data and header(s):
+      | files           | testdata/page_1.pdf | file  |
+      | stampSource     | text                | field |
+      | stampExpression | CONFIDENTIAL        | field |
+    Then the response status code should be 200
+    Then the response header "Content-Type" should be "application/pdf"

test/integration/features/pdfengines_watermark.feature

@@ -0,0 +1,211 @@
+@pdfengines
+@pdfengines-watermark
+@watermark
+Feature: /forms/pdfengines/watermark
+
+  Scenario: POST /forms/pdfengines/watermark (Text - pdfcpu)
+    Given I have a Gotenberg container with the following environment variable(s):
+      | PDFENGINES_WATERMARK_ENGINES | pdfcpu |
+    When I make a "POST" request to Gotenberg at the "/forms/pdfengines/watermark" endpoint with the following form data and header(s):
+      | files               | testdata/page_1.pdf | file  |
+      | watermarkSource     | text                | field |
+      | watermarkExpression | CONFIDENTIAL        | field |
+    Then the response status code should be 200
+    Then the response header "Content-Type" should be "application/pdf"
+    Then there should be 1 PDF(s) in the response
+    Then the "page_1.pdf" PDF should have 1 page(s)
+
+  Scenario: POST /forms/pdfengines/watermark (Text with Pages - pdfcpu)
+    Given I have a Gotenberg container with the following environment variable(s):
+      | PDFENGINES_WATERMARK_ENGINES | pdfcpu |
+    When I make a "POST" request to Gotenberg at the "/forms/pdfengines/watermark" endpoint with the following form data and header(s):
+      | files               | testdata/pages_3.pdf | file  |
+      | watermarkSource     | text                 | field |
+      | watermarkExpression | DRAFT                | field |
+      | watermarkPages      | 1-2                  | field |
+    Then the response status code should be 200
+    Then the response header "Content-Type" should be "application/pdf"
+    Then there should be 1 PDF(s) in the response
+    Then the "pages_3.pdf" PDF should have 3 page(s)
+
+  Scenario: POST /forms/pdfengines/watermark (Text with Options - pdfcpu)
+    Given I have a Gotenberg container with the following environment variable(s):
+      | PDFENGINES_WATERMARK_ENGINES | pdfcpu |
+    When I make a "POST" request to Gotenberg at the "/forms/pdfengines/watermark" endpoint with the following form data and header(s):
+      | files               | testdata/page_1.pdf                                  | file  |
+      | watermarkSource     | text                                                 | field |
+      | watermarkExpression | SAMPLE                                               | field |
+      | watermarkOptions    | {"scale":"0.5 abs","rot":"45","fillcolor":"#FF0000"} | field |
+    Then the response status code should be 200
+    Then the response header "Content-Type" should be "application/pdf"
+    Then there should be 1 PDF(s) in the response
+
+  Scenario: POST /forms/pdfengines/watermark (Image - pdfcpu)
+    Given I have a Gotenberg container with the following environment variable(s):
+      | PDFENGINES_WATERMARK_ENGINES | pdfcpu |
+    When I make a "POST" request to Gotenberg at the "/forms/pdfengines/watermark" endpoint with the following form data and header(s):
+      | files           | testdata/page_1.pdf    | file  |
+      | watermarks      | testdata/watermark.png | file  |
+      | watermarkSource | image                  | field |
+    Then the response status code should be 200
+    Then the response header "Content-Type" should be "application/pdf"
+    Then there should be 1 PDF(s) in the response
+
+  Scenario: POST /forms/pdfengines/watermark (PDF - pdfcpu)
+    Given I have a Gotenberg container with the following environment variable(s):
+      | PDFENGINES_WATERMARK_ENGINES | pdfcpu |
+    When I make a "POST" request to Gotenberg at the "/forms/pdfengines/watermark" endpoint with the following form data and header(s):
+      | files           | testdata/page_1.pdf | file  |
+      | watermarks      | testdata/page_2.pdf | file  |
+      | watermarkSource | pdf                 | field |
+    Then the response status code should be 200
+    Then the response header "Content-Type" should be "application/pdf"
+    Then there should be 1 PDF(s) in the response
+
+  Scenario: POST /forms/pdfengines/watermark (PDF - pdftk)
+    Given I have a Gotenberg container with the following environment variable(s):
+      | PDFENGINES_WATERMARK_ENGINES | pdftk |
+    When I make a "POST" request to Gotenberg at the "/forms/pdfengines/watermark" endpoint with the following form data and header(s):
+      | files           | testdata/page_1.pdf | file  |
+      | watermarks      | testdata/page_2.pdf | file  |
+      | watermarkSource | pdf                 | field |
+    Then the response status code should be 200
+    Then the response header "Content-Type" should be "application/pdf"
+    Then there should be 1 PDF(s) in the response
+
+  Scenario: POST /forms/pdfengines/watermark (Text - pdftk unsupported)
+    Given I have a Gotenberg container with the following environment variable(s):
+      | PDFENGINES_WATERMARK_ENGINES | pdftk |
+    When I make a "POST" request to Gotenberg at the "/forms/pdfengines/watermark" endpoint with the following form data and header(s):
+      | files               | testdata/page_1.pdf | file  |
+      | watermarkSource     | text                | field |
+      | watermarkExpression | CONFIDENTIAL        | field |
+    Then the response status code should be 400
+    Then the response body should match string:
+      """
+      At least one PDF engine cannot process the requested stamp source type, while others may have failed due to different issues
+      """
+
+  Scenario: POST /forms/pdfengines/watermark (Many PDFs)
+    Given I have a default Gotenberg container
+    When I make a "POST" request to Gotenberg at the "/forms/pdfengines/watermark" endpoint with the following form data and header(s):
+      | files               | testdata/page_1.pdf | file  |
+      | files               | testdata/page_2.pdf | file  |
+      | watermarkSource     | text                | field |
+      | watermarkExpression | DRAFT               | field |
+    Then the response status code should be 200
+    Then the response header "Content-Type" should be "application/zip"
+    Then there should be 2 PDF(s) in the response
+
+  Scenario: POST /forms/pdfengines/watermark (Bad Request - No Source)
+    Given I have a default Gotenberg container
+    When I make a "POST" request to Gotenberg at the "/forms/pdfengines/watermark" endpoint with the following form data and header(s):
+      | files | testdata/page_1.pdf | file |
+    Then the response status code should be 400
+    Then the response body should match string:
+      """
+      Invalid form data: form field 'watermarkSource' is required
+      """
+
+  Scenario: POST /forms/pdfengines/watermark (Bad Request - Invalid Source)
+    Given I have a default Gotenberg container
+    When I make a "POST" request to Gotenberg at the "/forms/pdfengines/watermark" endpoint with the following form data and header(s):
+      | files           | testdata/page_1.pdf | file  |
+      | watermarkSource | foo                 | field |
+    Then the response status code should be 400
+    Then the response body should contain string:
+      """
+      Invalid form data: form field 'watermarkSource' is invalid
+      """
+
+  Scenario: POST /forms/pdfengines/watermark (Bad Request - Missing File for Image Source)
+    Given I have a default Gotenberg container
+    When I make a "POST" request to Gotenberg at the "/forms/pdfengines/watermark" endpoint with the following form data and header(s):
+      | files           | testdata/page_1.pdf | file  |
+      | watermarkSource | image               | field |
+    Then the response status code should be 400
+    Then the response body should match string:
+      """
+      Invalid form data: a watermark file is required for image or pdf source
+      """
+
+  Scenario: POST /forms/pdfengines/watermark (Bad Request - Missing File for PDF Source)
+    Given I have a default Gotenberg container
+    When I make a "POST" request to Gotenberg at the "/forms/pdfengines/watermark" endpoint with the following form data and header(s):
+      | files           | testdata/page_1.pdf | file  |
+      | watermarkSource | pdf                 | field |
+    Then the response status code should be 400
+    Then the response body should match string:
+      """
+      Invalid form data: a watermark file is required for image or pdf source
+      """
+
+  Scenario: POST /forms/pdfengines/watermark (Bad Request - No PDF)
+    Given I have a default Gotenberg container
+    When I make a "POST" request to Gotenberg at the "/forms/pdfengines/watermark" endpoint with the following form data and header(s):
+      | watermarkSource     | text         | field |
+      | watermarkExpression | CONFIDENTIAL | field |
+    Then the response status code should be 400
+    Then the response body should match string:
+      """
+      Invalid form data: no form file found for extensions: [.pdf]
+      """
+
+  Scenario: POST /forms/pdfengines/watermark (Routes Disabled)
+    Given I have a Gotenberg container with the following environment variable(s):
+      | PDFENGINES_DISABLE_ROUTES | true |
+    When I make a "POST" request to Gotenberg at the "/forms/pdfengines/watermark" endpoint with the following form data and header(s):
+      | files               | testdata/page_1.pdf | file  |
+      | watermarkSource     | text                | field |
+      | watermarkExpression | CONFIDENTIAL        | field |
+    Then the response status code should be 404
+
+  Scenario: POST /forms/pdfengines/watermark (Gotenberg Trace)
+    Given I have a default Gotenberg container
+    When I make a "POST" request to Gotenberg at the "/forms/pdfengines/watermark" endpoint with the following form data and header(s):
+      | files               | testdata/page_1.pdf        | file   |
+      | watermarkSource     | text                       | field  |
+      | watermarkExpression | CONFIDENTIAL               | field  |
+      | Gotenberg-Trace     | forms_pdfengines_watermark | header |
+    Then the response status code should be 200
+    Then the response header "Content-Type" should be "application/pdf"
+    Then the response header "Gotenberg-Trace" should be "forms_pdfengines_watermark"
+    Then the Gotenberg container should log the following entries:
+      | "trace":"forms_pdfengines_watermark" |
+
+  @webhook
+  Scenario: POST /forms/pdfengines/watermark (Webhook)
+    Given I have a default Gotenberg container
+    Given I have a webhook server
+    When I make a "POST" request to Gotenberg at the "/forms/pdfengines/watermark" endpoint with the following form data and header(s):
+      | files                       | testdata/page_1.pdf                          | file   |
+      | watermarkSource             | text                                         | field  |
+      | watermarkExpression         | CONFIDENTIAL                                 | field  |
+      | Gotenberg-Webhook-Url       | http://host.docker.internal:%d/webhook       | header |
+      | Gotenberg-Webhook-Error-Url | http://host.docker.internal:%d/webhook/error | header |
+    Then the response status code should be 204
+    When I wait for the asynchronous request to the webhook
+    Then the webhook request header "Content-Type" should be "application/pdf"
+    Then there should be 1 PDF(s) in the webhook request
+
+  Scenario: POST /forms/pdfengines/watermark (Basic Auth)
+    Given I have a Gotenberg container with the following environment variable(s):
+      | API_ENABLE_BASIC_AUTH             | true |
+      | GOTENBERG_API_BASIC_AUTH_USERNAME | foo  |
+      | GOTENBERG_API_BASIC_AUTH_PASSWORD | bar  |
+    When I make a "POST" request to Gotenberg at the "/forms/pdfengines/watermark" endpoint with the following form data and header(s):
+      | files               | testdata/page_1.pdf | file  |
+      | watermarkSource     | text                | field |
+      | watermarkExpression | CONFIDENTIAL        | field |
+    Then the response status code should be 401
+
+  Scenario: POST /foo/forms/pdfengines/watermark (Root Path)
+    Given I have a Gotenberg container with the following environment variable(s):
+      | API_ENABLE_DEBUG_ROUTE | true  |
+      | API_ROOT_PATH          | /foo/ |
+    When I make a "POST" request to Gotenberg at the "/foo/forms/pdfengines/watermark" endpoint with the following form data and header(s):
+      | files               | testdata/page_1.pdf | file  |
+      | watermarkSource     | text                | field |
+      | watermarkExpression | CONFIDENTIAL        | field |
+    Then the response status code should be 200
+    Then the response header "Content-Type" should be "application/pdf"