feat(pdfengines): add embed feature

pkg/modules/api/context.go

@@ -38,11 +38,12 @@ var (
 
 // Context is the request context for a "multipart/form-data" requests.
 type Context struct {
-	dirPath     string
-	values      map[string][]string
-	files       map[string]string
-	outputPaths []string
-	cancelled   bool
+	dirPath      string
+	values       map[string][]string
+	files        map[string]string
+	filesByField map[string][]string
+	outputPaths  []string
+	cancelled    bool
 
 	logger     *zap.Logger
 	echoCtx    echo.Context
@@ -79,6 +80,9 @@ type downloadFrom struct {
 
 	// ExtraHttpHeaders are the HTTP headers to send alongside.
 	ExtraHttpHeaders map[string]string `json:"extraHttpHeaders"`
+
+	// Download as embed file
+	Embedded bool `json:"embedded"`
 }
 
 // newContext returns a [Context] by parsing a "multipart/form-data" request.
@@ -184,6 +188,7 @@ func newContext(echoCtx echo.Context, logger *zap.Logger, fs *gotenberg.FileSyst
 	ctx.dirPath = dirPath
 	ctx.values = form.Value
 	ctx.files = make(map[string]string)
+	ctx.filesByField = make(map[string][]string)
 
 	// First, try to download files listed in the "downloadFrom" form field, if
 	// any.
@@ -318,6 +323,9 @@ func newContext(echoCtx echo.Context, logger *zap.Logger, fs *gotenberg.FileSyst
 				}
 
 				ctx.files[filename] = path
+				if dl.Embedded {
+					ctx.filesByField[EmbedsFormField] = append(ctx.filesByField[EmbedsFormField], path)
+				}
 
 				return nil
 			})
@@ -373,17 +381,22 @@ func newContext(echoCtx echo.Context, logger *zap.Logger, fs *gotenberg.FileSyst
 	}
 
 	// Then, copy the form files, if any.
-	for _, files := range form.File {
+	for fieldName, files := range form.File {
 		for _, fh := range files {
 			err = copyToDisk(fh)
 			if err != nil {
 				return ctx, cancel, fmt.Errorf("copy to disk: %w", err)
 			}
+			// Track files by field name
+			filename := norm.NFC.String(filepath.Base(fh.Filename))
+			filePath := ctx.files[filename]
+			ctx.filesByField[fieldName] = append(ctx.filesByField[fieldName], filePath)
 		}
 	}
 
 	ctx.Log().Debug(fmt.Sprintf("form fields: %+v", ctx.values))
 	ctx.Log().Debug(fmt.Sprintf("form files: %+v", ctx.files))
+	ctx.Log().Debug(fmt.Sprintf("form files by field: %+v", ctx.filesByField))
 	ctx.Log().Debug(fmt.Sprintf("total bytes: %d", totalBytesRead.Load()))
 
 	return ctx, cancel, err
@@ -397,9 +410,10 @@ func (ctx *Context) Request() *http.Request {
 // FormData return a [FormData].
 func (ctx *Context) FormData() *FormData {
 	return &FormData{
-		values: ctx.values,
-		files:  ctx.files,
-		errors: nil,
+		values:       ctx.values,
+		files:        ctx.files,
+		filesByField: ctx.filesByField,
+		errors:       nil,
 	}
 }
 

pkg/modules/api/formdata.go

@@ -6,6 +6,7 @@ import (
 	"net/http"
 	"os"
 	"path/filepath"
+	"slices"
 	"sort"
 	"strconv"
 	"strings"
@@ -16,14 +17,20 @@ import (
 	"github.com/gotenberg/gotenberg/v8/pkg/gotenberg"
 )
 
+// EmbedsFormField represents the form field name for embedding files.
+const (
+	EmbedsFormField string = "embeds"
+)
+
 // FormData is a helper for validating and hydrating values from a
 // "multipart/form-data" request.
 //
 //	form := ctx.FormData()
 type FormData struct {
-	values map[string][]string
-	files  map[string]string
-	errors error
+	values       map[string][]string
+	files        map[string]string
+	filesByField map[string][]string
+	errors       error
 }
 
 // Validate returns nil or an error related to the [FormData] values, with a
@@ -358,6 +365,26 @@ func (form *FormData) Paths(extensions []string, target *[]string) *FormData {
 	return form.paths(extensions, target)
 }
 
+// Embeds binds the absolute paths of form data files that should be
+// embedded in the PDF. Only files uploaded with the "embeds" field name
+// will be included.
+//
+//	var embeds []string
+//
+//	ctx.FormData().Embeds(&embeds)
+func (form *FormData) Embeds(target *[]string) *FormData {
+	if form.errors != nil {
+		return form
+	}
+
+	// Get files from the "embeds" field
+	if paths, ok := form.filesByField[EmbedsFormField]; ok {
+		*target = append(*target, paths...)
+	}
+
+	return form
+}
+
 // MandatoryPaths binds the absolute paths of form data files, according to a
 // list of file extensions, to a string slice variable. It populates an error
 // if there is no file for given file extensions.
@@ -381,8 +408,15 @@ func (form *FormData) MandatoryPaths(extensions []string, target *[]string) *For
 
 // paths bind the absolute paths of form data files, according to a list of
 // file extensions, to a string slice variable.
+// embeds are excluded.
 func (form *FormData) paths(extensions []string, target *[]string) *FormData {
+	embeds, ok := form.filesByField[EmbedsFormField]
+
 	for filename, path := range form.files {
+		if ok && slices.Contains(embeds, path) {
+			continue
+		}
+
 		for _, ext := range extensions {
 			// See https://github.com/gotenberg/gotenberg/issues/228.
 			if strings.ToLower(filepath.Ext(filename)) == ext {

pkg/modules/api/formdata_test.go

@@ -1612,6 +1612,24 @@ func TestFormData_Paths(t *testing.T) {
 			},
 			expectCount: 2,
 		},
+		{
+			scenario: "files except embeds",
+			form: &FormData{
+				files: map[string]string{
+					"foo.pdf":     "/foo.pdf",
+					"embed_1.pdf": "/embed_1.pdf",
+					"embed_2.xml": "/embed_2.xml",
+				},
+				filesByField: map[string][]string{
+					"embeds": {"/embed_1.pdf", "/embed_2.xml"},
+				},
+			},
+			extensions: []string{".pdf"},
+			expect: []string{
+				"/foo.pdf",
+			},
+			expectCount: 1,
+		},
 	} {
 		t.Run(tc.scenario, func(t *testing.T) {
 			var actual []string
@@ -1740,3 +1758,28 @@ func TestFormData_mustAssign(t *testing.T) {
 	var target []string
 	form.mustAssign("foo", "foo", &target)
 }
+
+func TestFormData_Embeds(t *testing.T) {
+	expected := []string{"/bar.xml", "/baz.xml"}
+
+	var actual []string
+	form := &FormData{
+		files: map[string]string{
+			"foo.pdf": "/foo.pdf",
+			"bar.xml": "/bar.xml",
+			"baz.xml": "/baz.xml",
+		},
+		filesByField: map[string][]string{
+			"embeds": {"/bar.xml", "/baz.xml"},
+		},
+	}
+	form.Embeds(&actual)
+
+	if len(actual) != len(expected) {
+		t.Errorf("expected %d embeds but got %d", len(expected), len(actual))
+	}
+
+	if !reflect.DeepEqual(actual, expected) {
+		t.Errorf("expected %v but got %v", expected, actual)
+	}
+}

pkg/modules/chromium/routes.go

@@ -361,6 +361,7 @@ func convertUrlRoute(chromium Api, engine gotenberg.PdfEngine) api.Route {
 			pdfFormats := pdfengines.FormDataPdfFormats(form)
 			metadata := pdfengines.FormDataPdfMetadata(form, false)
 			userPassword, ownerPassword := pdfengines.FormDataPdfEncrypt(form)
+			embedPaths := pdfengines.FormDataPdfEmbeds(form)
 
 			var url string
 			err := form.
@@ -370,7 +371,7 @@ 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)
+			err = convertUrl(ctx, chromium, engine, url, options, mode, pdfFormats, metadata, userPassword, ownerPassword, embedPaths)
 			if err != nil {
 				return fmt.Errorf("convert URL to PDF: %w", err)
 			}
@@ -423,6 +424,7 @@ func convertHtmlRoute(chromium Api, engine gotenberg.PdfEngine) api.Route {
 			pdfFormats := pdfengines.FormDataPdfFormats(form)
 			metadata := pdfengines.FormDataPdfMetadata(form, false)
 			userPassword, ownerPassword := pdfengines.FormDataPdfEncrypt(form)
+			embedPaths := pdfengines.FormDataPdfEmbeds(form)
 
 			var inputPath string
 			err := form.
@@ -433,7 +435,7 @@ func convertHtmlRoute(chromium Api, engine gotenberg.PdfEngine) api.Route {
 			}
 
 			url := fmt.Sprintf("file://%s", inputPath)
-			err = convertUrl(ctx, chromium, engine, url, options, mode, pdfFormats, metadata, userPassword, ownerPassword)
+			err = convertUrl(ctx, chromium, engine, url, options, mode, pdfFormats, metadata, userPassword, ownerPassword, embedPaths)
 			if err != nil {
 				return fmt.Errorf("convert HTML to PDF: %w", err)
 			}
@@ -487,6 +489,7 @@ func convertMarkdownRoute(chromium Api, engine gotenberg.PdfEngine) api.Route {
 			pdfFormats := pdfengines.FormDataPdfFormats(form)
 			metadata := pdfengines.FormDataPdfMetadata(form, false)
 			userPassword, ownerPassword := pdfengines.FormDataPdfEncrypt(form)
+			embedPaths := pdfengines.FormDataPdfEmbeds(form)
 
 			var (
 				inputPath     string
@@ -506,7 +509,7 @@ func convertMarkdownRoute(chromium Api, engine gotenberg.PdfEngine) api.Route {
 				return fmt.Errorf("transform markdown file(s) to HTML: %w", err)
 			}
 
-			err = convertUrl(ctx, chromium, engine, url, options, mode, pdfFormats, metadata, userPassword, ownerPassword)
+			err = convertUrl(ctx, chromium, engine, url, options, mode, pdfFormats, metadata, userPassword, ownerPassword, embedPaths)
 			if err != nil {
 				return fmt.Errorf("convert markdown to PDF: %w", err)
 			}
@@ -630,7 +633,7 @@ 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]interface{}, userPassword, ownerPassword 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]interface{}, userPassword, ownerPassword string, embedPaths []string) error {
 	outputPath := ctx.GeneratePath(".pdf")
 	// See https://github.com/gotenberg/gotenberg/issues/1130.
 	filename := ctx.OutputFilename(outputPath)
@@ -687,6 +690,11 @@ func convertUrl(ctx *api.Context, chromium Api, engine gotenberg.PdfEngine, url
 		return fmt.Errorf("write metadata: %w", err)
 	}
 
+	err = pdfengines.EmbedFilesStub(ctx, engine, embedPaths, convertOutputPaths)
+	if err != nil {
+		return fmt.Errorf("embed files into PDFs: %w", err)
+	}
+
 	err = pdfengines.EncryptPdfStub(ctx, engine, userPassword, ownerPassword, convertOutputPaths)
 	if err != nil {
 		return fmt.Errorf("encrypt PDFs: %w", err)

pkg/modules/exiftool/exiftool.go

@@ -181,6 +181,11 @@ func (engine *ExifTool) Encrypt(ctx context.Context, logger *zap.Logger, inputPa
 	return fmt.Errorf("encrypt PDF using ExifTool: %w", gotenberg.ErrPdfEncryptionNotSupported)
 }
 
+// EmbedFiles is not available in this implementation.
+func (engine *ExifTool) EmbedFiles(ctx context.Context, logger *zap.Logger, filePaths []string, inputPath string) error {
+	return fmt.Errorf("embed files with ExifTool: %w", gotenberg.ErrPdfEngineMethodNotSupported)
+}
+
 // Interface guards.
 var (
 	_ gotenberg.Module      = (*ExifTool)(nil)

pkg/modules/libreoffice/pdfengine/pdfengine.go

@@ -96,6 +96,11 @@ func (engine *LibreOfficePdfEngine) Encrypt(ctx context.Context, logger *zap.Log
 	return fmt.Errorf("encrypt PDF using LibreOffice: %w", gotenberg.ErrPdfEngineMethodNotSupported)
 }
 
+// EmbedFiles is not available in this implementation.
+func (engine *LibreOfficePdfEngine) EmbedFiles(ctx context.Context, logger *zap.Logger, filePaths []string, inputPath string) error {
+	return fmt.Errorf("embed files with LibreOffice: %w", gotenberg.ErrPdfEngineMethodNotSupported)
+}
+
 // Interface guards.
 var (
 	_ gotenberg.Module      = (*LibreOfficePdfEngine)(nil)

pkg/modules/libreoffice/routes.go

@@ -31,6 +31,7 @@ func convertRoute(libreOffice libreofficeapi.Uno, engine gotenberg.PdfEngine) ap
 			pdfFormats := pdfengines.FormDataPdfFormats(form)
 			metadata := pdfengines.FormDataPdfMetadata(form, false)
 			userPassword, ownerPassword := pdfengines.FormDataPdfEncrypt(form)
+			embedPaths := pdfengines.FormDataPdfEmbeds(form)
 
 			zeroValuedSplitMode := gotenberg.SplitMode{}
 
@@ -264,6 +265,11 @@ func convertRoute(libreOffice libreofficeapi.Uno, engine gotenberg.PdfEngine) ap
 				}
 			}
 
+			err = pdfengines.EmbedFilesStub(ctx, engine, embedPaths, outputPaths)
+			if err != nil {
+				return fmt.Errorf("embed files into PDFs: %w", err)
+			}
+
 			err = pdfengines.EncryptPdfStub(ctx, engine, userPassword, ownerPassword, outputPaths)
 			if err != nil {
 				return fmt.Errorf("encrypt PDFs: %w", err)

pkg/modules/pdfcpu/pdfcpu.go

@@ -171,6 +171,34 @@ func (engine *PdfCpu) WriteMetadata(ctx context.Context, logger *zap.Logger, met
 	return fmt.Errorf("write PDF metadata with pdfcpu: %w", gotenberg.ErrPdfEngineMethodNotSupported)
 }
 
+// EmbedFiles embeds files into a PDF. All files are embedded as file attachments
+// without modifying the main PDF content.
+func (engine *PdfCpu) EmbedFiles(ctx context.Context, logger *zap.Logger, filePaths []string, inputPath string) error {
+	if len(filePaths) == 0 {
+		return nil
+	}
+
+	logger.Debug(fmt.Sprintf("embedding %d file(s) to %s: %v", len(filePaths), inputPath, filePaths))
+
+	args := []string{
+		"attachments", "add",
+		inputPath,
+	}
+	args = append(args, filePaths...)
+
+	cmd, err := gotenberg.CommandContext(ctx, logger, engine.binPath, args...)
+	if err != nil {
+		return fmt.Errorf("create command for attaching files: %w", err)
+	}
+
+	_, err = cmd.Exec()
+	if err != nil {
+		return fmt.Errorf("attach files with pdfcpu: %w", err)
+	}
+
+	return nil
+}
+
 // Encrypt adds password protection to a PDF file using pdfcpu.
 func (engine *PdfCpu) Encrypt(ctx context.Context, logger *zap.Logger, inputPath, userPassword, ownerPassword string) error {
 	if userPassword == "" {

pkg/modules/pdfengines/multi.go

@@ -19,6 +19,7 @@ type multiPdfEngines struct {
 	readMetadataEngines  []gotenberg.PdfEngine
 	writeMetadataEngines []gotenberg.PdfEngine
 	passwordEngines      []gotenberg.PdfEngine
+	embedEngines         []gotenberg.PdfEngine
 }
 
 func newMultiPdfEngines(
@@ -28,7 +29,8 @@ func newMultiPdfEngines(
 	convertEngines,
 	readMetadataEngines,
 	writeMetadataEngines,
-	passwordEngines []gotenberg.PdfEngine,
+	passwordEngines,
+	embedEngines []gotenberg.PdfEngine,
 ) *multiPdfEngines {
 	return &multiPdfEngines{
 		mergeEngines:         mergeEngines,
@@ -38,6 +40,7 @@ func newMultiPdfEngines(
 		readMetadataEngines:  readMetadataEngines,
 		writeMetadataEngines: writeMetadataEngines,
 		passwordEngines:      passwordEngines,
+		embedEngines:         embedEngines,
 	}
 }
 
@@ -238,6 +241,31 @@ func (multi *multiPdfEngines) Encrypt(ctx context.Context, logger *zap.Logger, i
 	return fmt.Errorf("encrypt PDF using multi PDF engines: %w", err)
 }
 
+// EmbedFiles embeds files into a PDF using the first available
+// engine that supports file embedding.
+func (multi *multiPdfEngines) EmbedFiles(ctx context.Context, logger *zap.Logger, filePaths []string, inputPath string) error {
+	var err error
+	errChan := make(chan error, 1)
+
+	for _, engine := range multi.embedEngines {
+		go func(engine gotenberg.PdfEngine) {
+			errChan <- engine.EmbedFiles(ctx, logger, filePaths, inputPath)
+		}(engine)
+
+		select {
+		case embedErr := <-errChan:
+			errored := multierr.AppendInto(&err, embedErr)
+			if !errored {
+				return nil
+			}
+		case <-ctx.Done():
+			return ctx.Err()
+		}
+	}
+
+	return fmt.Errorf("embed files into PDF using multi PDF engines: %w", err)
+}
+
 // Interface guards.
 var (
 	_ gotenberg.PdfEngine = (*multiPdfEngines)(nil)

pkg/modules/pdfengines/pdfengines.go

@@ -34,6 +34,7 @@ type PdfEngines struct {
 	readMetadataNames  []string
 	writeMetadataNames []string
 	encryptNames       []string
+	embedNames         []string
 	engines            []gotenberg.PdfEngine
 	disableRoutes      bool
 }
@@ -51,6 +52,7 @@ func (mod *PdfEngines) Descriptor() gotenberg.ModuleDescriptor {
 			fs.StringSlice("pdfengines-read-metadata-engines", []string{"exiftool"}, "Set the PDF engines and their order for the read metadata feature - empty means all")
 			fs.StringSlice("pdfengines-write-metadata-engines", []string{"exiftool"}, "Set the PDF engines and their order for the write metadata feature - empty means all")
 			fs.StringSlice("pdfengines-encrypt-engines", []string{"qpdf", "pdftk", "pdfcpu"}, "Set the PDF engines and their order for the password protection feature - empty means all")
+			fs.StringSlice("pdfengines-embed-engines", []string{"pdfcpu"}, "Set the PDF engines and their order for the file embedding feature - empty means all")
 			fs.Bool("pdfengines-disable-routes", false, "Disable the routes")
 
 			// Deprecated flags.
@@ -77,6 +79,7 @@ func (mod *PdfEngines) Provision(ctx *gotenberg.Context) error {
 	readMetadataNames := flags.MustStringSlice("pdfengines-read-metadata-engines")
 	writeMetadataNames := flags.MustStringSlice("pdfengines-write-metadata-engines")
 	encryptNames := flags.MustStringSlice("pdfengines-encrypt-engines")
+	embedNames := flags.MustStringSlice("pdfengines-embed-engines")
 	mod.disableRoutes = flags.MustBool("pdfengines-disable-routes")
 
 	engines, err := ctx.Modules(new(gotenberg.PdfEngine))
@@ -138,6 +141,11 @@ func (mod *PdfEngines) Provision(ctx *gotenberg.Context) error {
 		mod.encryptNames = encryptNames
 	}
 
+	mod.embedNames = defaultNames
+	if len(embedNames) > 0 {
+		mod.embedNames = embedNames
+	}
+
 	return nil
 }
 
@@ -192,6 +200,7 @@ func (mod *PdfEngines) Validate() error {
 	findNonExistingEngines(mod.readMetadataNames)
 	findNonExistingEngines(mod.writeMetadataNames)
 	findNonExistingEngines(mod.encryptNames)
+	findNonExistingEngines(mod.embedNames)
 
 	if len(nonExistingEngines) == 0 {
 		return nil
@@ -238,6 +247,7 @@ func (mod *PdfEngines) PdfEngine() (gotenberg.PdfEngine, error) {
 		engines(mod.readMetadataNames),
 		engines(mod.writeMetadataNames),
 		engines(mod.encryptNames),
+		engines(mod.embedNames),
 	), nil
 }
 
@@ -262,6 +272,7 @@ func (mod *PdfEngines) Routes() ([]api.Route, error) {
 		readMetadataRoute(engine),
 		writeMetadataRoute(engine),
 		encryptRoute(engine),
+		embedRoute(engine),
 	}, nil
 }
 

pkg/modules/pdfengines/routes.go

@@ -254,6 +254,14 @@ func WriteMetadataStub(ctx *api.Context, engine gotenberg.PdfEngine, metadata ma
 	return nil
 }
 
+// FormDataPdfEmbeds extracts embedded file paths from form data.
+// Only files uploaded with the "embeds" field name are included.
+func FormDataPdfEmbeds(form *api.FormData) []string {
+	var embedPaths []string
+	form.Embeds(&embedPaths)
+	return embedPaths
+}
+
 // FormDataPdfEncrypt extracts encryption parameters from form data.
 func FormDataPdfEncrypt(form *api.FormData) (userPassword, ownerPassword string) {
 	form.String("userPassword", &userPassword, "")
@@ -277,6 +285,22 @@ func EncryptPdfStub(ctx *api.Context, engine gotenberg.PdfEngine, userPassword,
 	return nil
 }
 
+// EmbedFilesStub embeds files into PDF files.
+func EmbedFilesStub(ctx *api.Context, engine gotenberg.PdfEngine, embedPaths []string, inputPaths []string) error {
+	if len(embedPaths) == 0 {
+		return nil
+	}
+
+	for _, inputPath := range inputPaths {
+		err := engine.EmbedFiles(ctx, ctx.Log(), embedPaths, inputPath)
+		if err != nil {
+			return fmt.Errorf("embed files into PDF '%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{
@@ -290,6 +314,7 @@ func mergeRoute(engine gotenberg.PdfEngine) api.Route {
 			pdfFormats := FormDataPdfFormats(form)
 			metadata := FormDataPdfMetadata(form, false)
 			userPassword, ownerPassword := FormDataPdfEncrypt(form)
+			embedPaths := FormDataPdfEmbeds(form)
 
 			var inputPaths []string
 			var flatten bool
@@ -324,6 +349,11 @@ func mergeRoute(engine gotenberg.PdfEngine) api.Route {
 				}
 			}
 
+			err = EmbedFilesStub(ctx, engine, embedPaths, outputPaths)
+			if err != nil {
+				return fmt.Errorf("embed files into PDFs: %w", err)
+			}
+
 			err = EncryptPdfStub(ctx, engine, userPassword, ownerPassword, outputPaths)
 			if err != nil {
 				return fmt.Errorf("encrypt PDFs: %w", err)
@@ -353,6 +383,7 @@ func splitRoute(engine gotenberg.PdfEngine) api.Route {
 			pdfFormats := FormDataPdfFormats(form)
 			metadata := FormDataPdfMetadata(form, false)
 			userPassword, ownerPassword := FormDataPdfEncrypt(form)
+			embedPaths := FormDataPdfEmbeds(form)
 
 			var inputPaths []string
 			var flatten bool
@@ -386,6 +417,11 @@ func splitRoute(engine gotenberg.PdfEngine) api.Route {
 				}
 			}
 
+			err = EmbedFilesStub(ctx, engine, embedPaths, convertOutputPaths)
+			if err != nil {
+				return fmt.Errorf("embed files into PDFs: %w", err)
+			}
+
 			err = EncryptPdfStub(ctx, engine, userPassword, ownerPassword, convertOutputPaths)
 			if err != nil {
 				return fmt.Errorf("encrypt PDFs: %w", err)
@@ -620,3 +656,38 @@ func encryptRoute(engine gotenberg.PdfEngine) api.Route {
 		},
 	}
 }
+
+// embedRoute returns an [api.Route] which can add embedded files to PDFs.
+func embedRoute(engine gotenberg.PdfEngine) api.Route {
+	return api.Route{
+		Method:      http.MethodPost,
+		Path:        "/forms/pdfengines/embed",
+		IsMultipart: true,
+		Handler: func(c echo.Context) error {
+			ctx := c.Get("context").(*api.Context)
+
+			form := ctx.FormData()
+			embedPaths := FormDataPdfEmbeds(form)
+
+			var inputPaths []string
+			err := form.
+				MandatoryPaths([]string{".pdf"}, &inputPaths).
+				Validate()
+			if err != nil {
+				return fmt.Errorf("validate form data: %w", err)
+			}
+
+			err = EmbedFilesStub(ctx, engine, embedPaths, inputPaths)
+			if err != nil {
+				return fmt.Errorf("embed files into 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

@@ -183,6 +183,11 @@ func (engine *PdfTk) Encrypt(ctx context.Context, logger *zap.Logger, inputPath,
 	return nil
 }
 
+// EmbedFiles is not available in this implementation.
+func (engine *PdfTk) EmbedFiles(ctx context.Context, logger *zap.Logger, filePaths []string, inputPath string) error {
+	return fmt.Errorf("embed files with PDFtk: %w", gotenberg.ErrPdfEngineMethodNotSupported)
+}
+
 // Interface guards.
 var (
 	_ gotenberg.Module      = (*PdfTk)(nil)

pkg/modules/qpdf/qpdf.go

@@ -201,6 +201,11 @@ func (engine *QPdf) Encrypt(ctx context.Context, logger *zap.Logger, inputPath,
 	return nil
 }
 
+// EmbedFiles is not available in this implementation.
+func (engine *QPdf) EmbedFiles(ctx context.Context, logger *zap.Logger, filePaths []string, inputPath string) error {
+	return fmt.Errorf("embed files with QPDF: %w", gotenberg.ErrPdfEngineMethodNotSupported)
+}
+
 var (
 	_ gotenberg.Module      = (*QPdf)(nil)
 	_ gotenberg.Provisioner = (*QPdf)(nil)