feat(pdfengines): add rotate feature

Makefile

@@ -69,6 +69,7 @@ PDFENGINES_WRITE_BOOKMARKS_ENGINES=pdfcpu
 PDFENGINES_WATERMARK_ENGINES=pdfcpu,pdftk
 PDFENGINES_STAMP_ENGINES=pdfcpu,pdftk
 PDFENGINES_ENCRYPT_ENGINES=qpdf,pdfcpu,pdftk
+PDFENGINES_ROTATE_ENGINES=pdfcpu,pdftk
 PDFENGINES_EMBED_ENGINES=pdfcpu
 PROMETHEUS_NAMESPACE=gotenberg
 PROMETHEUS_COLLECT_INTERVAL=1s
@@ -151,6 +152,7 @@ run: ## Start a Gotenberg container
 	--pdfengines-watermark-engines=$(PDFENGINES_WATERMARK_ENGINES) \
 	--pdfengines-stamp-engines=$(PDFENGINES_STAMP_ENGINES) \
 	--pdfengines-encrypt-engines=$(PDFENGINES_ENCRYPT_ENGINES) \
+	--pdfengines-rotate-engines=$(PDFENGINES_ROTATE_ENGINES) \
 	--pdfengines-embed-engines=$(PDFENGINES_EMBED_ENGINES) \
 	--prometheus-namespace=$(PROMETHEUS_NAMESPACE) \
 	--prometheus-collect-interval=$(PROMETHEUS_COLLECT_INTERVAL) \
@@ -203,6 +205,8 @@ NO_CONCURRENCY=false
 # watermark
 # pdfengines-stamp
 # stamp
+# pdfengines-rotate
+# rotate
 # pdfengines-bookmarks
 # bookmarks
 # prometheus-metrics

pkg/gotenberg/mocks.go

@@ -59,6 +59,7 @@ type PdfEngineMock struct {
 	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
+	RotateMock         func(ctx context.Context, logger *zap.Logger, inputPath string, angle int, pages string) error
 }
 
 func (engine *PdfEngineMock) Merge(ctx context.Context, logger *zap.Logger, inputPaths []string, outputPath string) error {
@@ -113,6 +114,10 @@ func (engine *PdfEngineMock) Stamp(ctx context.Context, logger *zap.Logger, inpu
 	return engine.StampMock(ctx, logger, inputPath, stamp)
 }
 
+func (engine *PdfEngineMock) Rotate(ctx context.Context, logger *zap.Logger, inputPath string, angle int, pages string) error {
+	return engine.RotateMock(ctx, logger, inputPath, angle, pages)
+}
+
 // PdfEngineProviderMock is a mock for the [PdfEngineProvider] interface.
 type PdfEngineProviderMock struct {
 	PdfEngineMock func() (PdfEngine, error)

pkg/gotenberg/pdfengine.go

@@ -32,6 +32,10 @@ var (
 	// ErrPdfStampSourceNotSupported is returned when a stamp source type
 	// is not supported by the PDF engine.
 	ErrPdfStampSourceNotSupported = errors.New("stamp source not supported")
+
+	// ErrPdfRotateAngleNotSupported is returned when the rotation angle is
+	// not supported.
+	ErrPdfRotateAngleNotSupported = errors.New("rotation angle not supported")
 )
 
 // PdfEngineInvalidArgsError represents an error returned by a PDF engine when
@@ -203,6 +207,10 @@ type PdfEngine interface {
 
 	// 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
+
+	// Rotate rotates pages of a PDF file by the given angle (90, 180, 270).
+	// If pages is empty, all pages are rotated.
+	Rotate(ctx context.Context, logger *zap.Logger, inputPath string, angle int, pages string) error
 }
 
 // PdfEngineProvider offers an interface to instantiate a [PdfEngine].

pkg/modules/api/middlewares.go

@@ -65,6 +65,10 @@ func ParseError(err error) (int, string) {
 		return http.StatusBadRequest, "At least one PDF engine cannot process the requested stamp source type, while others may have failed due to different issues"
 	}
 
+	if errors.Is(err, gotenberg.ErrPdfRotateAngleNotSupported) {
+		return http.StatusBadRequest, "At least one PDF engine cannot process the requested rotation angle, 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

@@ -419,6 +419,7 @@ func convertUrlRoute(chromium Api, engine gotenberg.PdfEngine) api.Route {
 			watermarkFiles := pdfengines.FormDataPdfWatermarkFiles(form)
 			stamp := pdfengines.FormDataPdfStamp(form, false)
 			stampFiles := pdfengines.FormDataPdfStampFiles(form)
+			rotateAngle, rotatePages := pdfengines.FormDataPdfRotate(form, false)
 
 			var url string
 			err := form.
@@ -435,7 +436,7 @@ func convertUrlRoute(chromium Api, engine gotenberg.PdfEngine) api.Route {
 				stamp.Expression = stampFiles[0]
 			}
 
-			err = convertUrl(ctx, chromium, engine, url, options, mode, pdfFormats, metadata, userPassword, ownerPassword, embedPaths, watermark, stamp)
+			err = convertUrl(ctx, chromium, engine, url, options, mode, pdfFormats, metadata, userPassword, ownerPassword, embedPaths, watermark, stamp, rotateAngle, rotatePages)
 			if err != nil {
 				return fmt.Errorf("convert URL to PDF: %w", err)
 			}
@@ -493,6 +494,7 @@ func convertHtmlRoute(chromium Api, engine gotenberg.PdfEngine) api.Route {
 			watermarkFiles := pdfengines.FormDataPdfWatermarkFiles(form)
 			stamp := pdfengines.FormDataPdfStamp(form, false)
 			stampFiles := pdfengines.FormDataPdfStampFiles(form)
+			rotateAngle, rotatePages := pdfengines.FormDataPdfRotate(form, false)
 
 			var inputPath string
 			err := form.
@@ -510,7 +512,7 @@ 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, embedPaths, watermark, stamp)
+			err = convertUrl(ctx, chromium, engine, url, options, mode, pdfFormats, metadata, userPassword, ownerPassword, embedPaths, watermark, stamp, rotateAngle, rotatePages)
 			if err != nil {
 				return fmt.Errorf("convert HTML to PDF: %w", err)
 			}
@@ -569,6 +571,7 @@ func convertMarkdownRoute(chromium Api, engine gotenberg.PdfEngine) api.Route {
 			watermarkFiles := pdfengines.FormDataPdfWatermarkFiles(form)
 			stamp := pdfengines.FormDataPdfStamp(form, false)
 			stampFiles := pdfengines.FormDataPdfStampFiles(form)
+			rotateAngle, rotatePages := pdfengines.FormDataPdfRotate(form, false)
 
 			var (
 				inputPath     string
@@ -595,7 +598,7 @@ 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, embedPaths, watermark, stamp)
+			err = convertUrl(ctx, chromium, engine, url, options, mode, pdfFormats, metadata, userPassword, ownerPassword, embedPaths, watermark, stamp, rotateAngle, rotatePages)
 			if err != nil {
 				return fmt.Errorf("convert markdown to PDF: %w", err)
 			}
@@ -719,7 +722,7 @@ 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, watermark, stamp gotenberg.Stamp) 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, rotateAngle int, rotatePages string) error {
 	outputPath := ctx.GeneratePath(".pdf")
 	// See https://github.com/gotenberg/gotenberg/issues/1130.
 	filename := ctx.OutputFilename(outputPath)
@@ -801,6 +804,11 @@ func convertUrl(ctx *api.Context, chromium Api, engine gotenberg.PdfEngine, url
 		return fmt.Errorf("stamp PDFs: %w", err)
 	}
 
+	err = pdfengines.RotateStub(ctx, engine, rotateAngle, rotatePages, outputPaths)
+	if err != nil {
+		return fmt.Errorf("rotate PDFs: %w", err)
+	}
+
 	convertOutputPaths, err := pdfengines.ConvertStub(ctx, engine, pdfFormats, outputPaths)
 	if err != nil {
 		return fmt.Errorf("convert PDF(s): %w", err)

pkg/modules/exiftool/exiftool.go

@@ -264,6 +264,11 @@ func (engine *ExifTool) Stamp(ctx context.Context, logger *zap.Logger, inputPath
 	return fmt.Errorf("stamp PDF with ExifTool: %w", gotenberg.ErrPdfEngineMethodNotSupported)
 }
 
+// Rotate is not available in this implementation.
+func (engine *ExifTool) Rotate(ctx context.Context, logger *zap.Logger, inputPath string, angle int, pages string) error {
+	return fmt.Errorf("rotate PDF with ExifTool: %w", gotenberg.ErrPdfEngineMethodNotSupported)
+}
+
 // Interface guards.
 var (
 	_ gotenberg.Module      = (*ExifTool)(nil)

pkg/modules/libreoffice/pdfengine/pdfengine.go

@@ -126,6 +126,11 @@ func (engine *LibreOfficePdfEngine) Stamp(ctx context.Context, logger *zap.Logge
 	return fmt.Errorf("stamp PDF with LibreOffice: %w", gotenberg.ErrPdfEngineMethodNotSupported)
 }
 
+// Rotate is not available in this implementation.
+func (engine *LibreOfficePdfEngine) Rotate(ctx context.Context, logger *zap.Logger, inputPath string, angle int, pages string) error {
+	return fmt.Errorf("rotate PDF with LibreOffice: %w", gotenberg.ErrPdfEngineMethodNotSupported)
+}
+
 // Interface guards.
 var (
 	_ gotenberg.Module      = (*LibreOfficePdfEngine)(nil)

pkg/modules/libreoffice/routes.go

@@ -36,6 +36,7 @@ func convertRoute(libreOffice libreofficeapi.Uno, engine gotenberg.PdfEngine) ap
 			watermarkFiles := pdfengines.FormDataPdfWatermarkFiles(form)
 			stamp := pdfengines.FormDataPdfStamp(form, false)
 			stampFiles := pdfengines.FormDataPdfStampFiles(form)
+			angle, rotatePages := pdfengines.FormDataPdfRotate(form, false)
 
 			zeroValuedSplitMode := gotenberg.SplitMode{}
 
@@ -200,7 +201,7 @@ func convertRoute(libreOffice libreofficeapi.Uno, engine gotenberg.PdfEngine) ap
 				return err
 			}
 
-			hasPostProcessing := watermark.Source != "" || stamp.Source != "" ||
+			hasPostProcessing := watermark.Source != "" || stamp.Source != "" || angle != 0 ||
 				len(embedPaths) > 0 || len(metadata) > 0 || flatten
 
 			outputPaths := make([]string, len(inputPaths))
@@ -317,6 +318,11 @@ func convertRoute(libreOffice libreofficeapi.Uno, engine gotenberg.PdfEngine) ap
 				return fmt.Errorf("stamp PDFs: %w", err)
 			}
 
+			err = pdfengines.RotateStub(ctx, engine, angle, rotatePages, outputPaths)
+			if err != nil {
+				return fmt.Errorf("rotate PDFs: %w", err)
+			}
+
 			if flatten {
 				err = pdfengines.FlattenStub(ctx, engine, outputPaths)
 				if err != nil {

pkg/modules/pdfcpu/pdfcpu.go

@@ -10,6 +10,7 @@ import (
 	"os/exec"
 	"path/filepath"
 	"sort"
+	"strconv"
 	"strings"
 	"syscall"
 
@@ -389,6 +390,27 @@ func (engine *PdfCpu) Stamp(ctx context.Context, logger *zap.Logger, inputPath s
 	return engine.applyStampOrWatermark(ctx, logger, "stamp", inputPath, stamp)
 }
 
+// Rotate rotates pages of a PDF file by the given angle using pdfcpu.
+func (engine *PdfCpu) Rotate(ctx context.Context, logger *zap.Logger, inputPath string, angle int, pages string) error {
+	args := []string{"rotate"}
+	if pages != "" {
+		args = append(args, "-pages", pages)
+	}
+	args = append(args, "--", inputPath, strconv.Itoa(angle), 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("rotate PDF with pdfcpu: %w", err)
+	}
+
+	return nil
+}
+
 func (engine *PdfCpu) applyStampOrWatermark(ctx context.Context, logger *zap.Logger, command string, inputPath string, stamp gotenberg.Stamp) error {
 	var mode string
 	switch stamp.Source {

pkg/modules/pdfengines/multi.go

@@ -24,6 +24,7 @@ type multiPdfEngines struct {
 	writeBookmarksEngines []gotenberg.PdfEngine
 	watermarkEngines      []gotenberg.PdfEngine
 	stampEngines          []gotenberg.PdfEngine
+	rotateEngines         []gotenberg.PdfEngine
 }
 
 func newMultiPdfEngines(
@@ -38,7 +39,8 @@ func newMultiPdfEngines(
 	readBookmarksEngines,
 	writeBookmarksEngines,
 	watermarkEngines,
-	stampEngines []gotenberg.PdfEngine,
+	stampEngines,
+	rotateEngines []gotenberg.PdfEngine,
 ) *multiPdfEngines {
 	return &multiPdfEngines{
 		mergeEngines:          mergeEngines,
@@ -53,6 +55,7 @@ func newMultiPdfEngines(
 		writeBookmarksEngines: writeBookmarksEngines,
 		watermarkEngines:      watermarkEngines,
 		stampEngines:          stampEngines,
+		rotateEngines:         rotateEngines,
 	}
 }
 
@@ -425,6 +428,31 @@ func (multi *multiPdfEngines) Stamp(ctx context.Context, logger *zap.Logger, inp
 	return fmt.Errorf("stamp PDF with multi PDF engines: %w", err)
 }
 
+// Rotate rotates pages of a PDF file using the first available engine that
+// supports rotation.
+func (multi *multiPdfEngines) Rotate(ctx context.Context, logger *zap.Logger, inputPath string, angle int, pages string) error {
+	var err error
+	errChan := make(chan error, 1)
+
+	for _, engine := range multi.rotateEngines {
+		go func(engine gotenberg.PdfEngine) {
+			errChan <- engine.Rotate(ctx, logger, inputPath, angle, pages)
+		}(engine)
+
+		select {
+		case rotateErr := <-errChan:
+			errored := multierr.AppendInto(&err, rotateErr)
+			if !errored {
+				return nil
+			}
+		case <-ctx.Done():
+			return ctx.Err()
+		}
+	}
+
+	return fmt.Errorf("rotate PDF with multi PDF engines: %w", err)
+}
+
 // Interface guards.
 var (
 	_ gotenberg.PdfEngine = (*multiPdfEngines)(nil)

pkg/modules/pdfengines/pdfengines.go

@@ -40,6 +40,7 @@ type PdfEngines struct {
 	writeBookmarksNames []string
 	watermarkNames      []string
 	stampNames          []string
+	rotateNames         []string
 	engines             []gotenberg.PdfEngine
 	disableRoutes       bool
 }
@@ -62,6 +63,7 @@ func (mod *PdfEngines) Descriptor() gotenberg.ModuleDescriptor {
 			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.StringSlice("pdfengines-rotate-engines", []string{"pdfcpu", "pdftk"}, "Set the PDF engines and their order for the rotate feature - empty means all")
 			fs.Bool("pdfengines-disable-routes", false, "Disable the routes")
 
 			// Deprecated flags.
@@ -93,6 +95,7 @@ func (mod *PdfEngines) Provision(ctx *gotenberg.Context) error {
 	writeBookmarksNames := flags.MustStringSlice("pdfengines-write-bookmarks-engines")
 	watermarkNames := flags.MustStringSlice("pdfengines-watermark-engines")
 	stampNames := flags.MustStringSlice("pdfengines-stamp-engines")
+	rotateNames := flags.MustStringSlice("pdfengines-rotate-engines")
 	mod.disableRoutes = flags.MustBool("pdfengines-disable-routes")
 
 	engines, err := ctx.Modules(new(gotenberg.PdfEngine))
@@ -179,6 +182,11 @@ func (mod *PdfEngines) Provision(ctx *gotenberg.Context) error {
 		mod.stampNames = stampNames
 	}
 
+	mod.rotateNames = defaultNames
+	if len(rotateNames) > 0 {
+		mod.rotateNames = rotateNames
+	}
+
 	return nil
 }
 
@@ -232,6 +240,7 @@ func (mod *PdfEngines) Validate() error {
 	findNonExistingEngines(mod.writeBookmarksNames)
 	findNonExistingEngines(mod.watermarkNames)
 	findNonExistingEngines(mod.stampNames)
+	findNonExistingEngines(mod.rotateNames)
 
 	if len(nonExistingEngines) == 0 {
 		return nil
@@ -256,6 +265,7 @@ func (mod *PdfEngines) SystemMessages() []string {
 		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[:], " ")),
+		fmt.Sprintf("rotate engines - %s", strings.Join(mod.rotateNames[:], " ")),
 	}
 }
 
@@ -288,6 +298,7 @@ func (mod *PdfEngines) PdfEngine() (gotenberg.PdfEngine, error) {
 		engines(mod.writeBookmarksNames),
 		engines(mod.watermarkNames),
 		engines(mod.stampNames),
+		engines(mod.rotateNames),
 	), nil
 }
 
@@ -317,6 +328,7 @@ func (mod *PdfEngines) Routes() ([]api.Route, error) {
 		embedRoute(engine),
 		watermarkRoute(engine),
 		stampRoute(engine),
+		rotateRoute(engine),
 	}, nil
 }
 

pkg/modules/pdfengines/routes.go

@@ -166,6 +166,56 @@ func FormDataPdfBookmarks(form *api.FormData, mandatory bool) any {
 	return bookmarks
 }
 
+// FormDataPdfRotate creates rotation parameters from the form data.
+func FormDataPdfRotate(form *api.FormData, mandatory bool) (int, string) {
+	var angle int
+	var pages string
+
+	angleFunc := func(value string) error {
+		if value == "" {
+			return nil
+		}
+		v, err := strconv.Atoi(value)
+		if err != nil {
+			return err
+		}
+		if v != 90 && v != 180 && v != 270 {
+			return errors.New("wrong value, expected 90, 180, or 270")
+		}
+		angle = v
+		return nil
+	}
+
+	if mandatory {
+		form.MandatoryCustom("rotateAngle", func(value string) error {
+			return angleFunc(value)
+		})
+	} else {
+		form.Custom("rotateAngle", func(value string) error {
+			return angleFunc(value)
+		})
+	}
+	form.String("rotatePages", &pages, "")
+
+	return angle, pages
+}
+
+// RotateStub rotates pages of PDF files. If angle is 0, it does nothing.
+func RotateStub(ctx *api.Context, engine gotenberg.PdfEngine, angle int, pages string, inputPaths []string) error {
+	if angle == 0 {
+		return nil
+	}
+
+	for _, inputPath := range inputPaths {
+		err := engine.Rotate(ctx, ctx.Log(), inputPath, angle, pages)
+		if err != nil {
+			return fmt.Errorf("rotate '%s': %w", inputPath, err)
+		}
+	}
+
+	return nil
+}
+
 // ValidatePdfFormatsCompat checks for incompatible combinations of PDF formats
 // with other features and returns an appropriate error if found.
 func ValidatePdfFormatsCompat(pdfFormats gotenberg.PdfFormats, userPassword string, embedPaths []string) error {
@@ -561,6 +611,7 @@ func mergeRoute(engine gotenberg.PdfEngine) api.Route {
 			watermarkFiles := FormDataPdfWatermarkFiles(form)
 			stamp := FormDataPdfStamp(form, false)
 			stampFiles := FormDataPdfStampFiles(form)
+			angle, rotatePages := FormDataPdfRotate(form, false)
 
 			var inputPaths []string
 			var flatten bool
@@ -604,6 +655,11 @@ func mergeRoute(engine gotenberg.PdfEngine) api.Route {
 				return fmt.Errorf("stamp PDFs: %w", err)
 			}
 
+			err = RotateStub(ctx, engine, angle, rotatePages, outputPaths)
+			if err != nil {
+				return fmt.Errorf("rotate PDFs: %w", err)
+			}
+
 			if flatten {
 				err = FlattenStub(ctx, engine, outputPaths)
 				if err != nil {
@@ -706,6 +762,7 @@ func splitRoute(engine gotenberg.PdfEngine) api.Route {
 			watermarkFiles := FormDataPdfWatermarkFiles(form)
 			stamp := FormDataPdfStamp(form, false)
 			stampFiles := FormDataPdfStampFiles(form)
+			angle, rotatePages := FormDataPdfRotate(form, false)
 
 			var inputPaths []string
 			var flatten bool
@@ -744,6 +801,11 @@ func splitRoute(engine gotenberg.PdfEngine) api.Route {
 				return fmt.Errorf("stamp PDFs: %w", err)
 			}
 
+			err = RotateStub(ctx, engine, angle, rotatePages, outputPaths)
+			if err != nil {
+				return fmt.Errorf("rotate PDFs: %w", err)
+			}
+
 			if flatten {
 				err = FlattenStub(ctx, engine, outputPaths)
 				if err != nil {
@@ -1216,3 +1278,38 @@ func stampRoute(engine gotenberg.PdfEngine) api.Route {
 		},
 	}
 }
+
+// rotateRoute returns an [api.Route] which can rotate pages of PDFs.
+func rotateRoute(engine gotenberg.PdfEngine) api.Route {
+	return api.Route{
+		Method:      http.MethodPost,
+		Path:        "/forms/pdfengines/rotate",
+		IsMultipart: true,
+		Handler: func(c echo.Context) error {
+			ctx := c.Get("context").(*api.Context)
+
+			form := ctx.FormData()
+			angle, pages := FormDataPdfRotate(form, true)
+
+			var inputPaths []string
+			err := form.
+				MandatoryPaths([]string{".pdf"}, &inputPaths).
+				Validate()
+			if err != nil {
+				return fmt.Errorf("validate form data: %w", err)
+			}
+
+			err = RotateStub(ctx, engine, angle, pages, inputPaths)
+			if err != nil {
+				return fmt.Errorf("rotate 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

@@ -261,6 +261,47 @@ func (engine *PdfTk) Stamp(ctx context.Context, logger *zap.Logger, inputPath st
 	return nil
 }
 
+// Rotate rotates all pages of a PDF file by the given angle using PDFtk.
+// Page-specific rotation is not supported; if pages is non-empty,
+// ErrPdfEngineMethodNotSupported is returned.
+func (engine *PdfTk) Rotate(ctx context.Context, logger *zap.Logger, inputPath string, angle int, pages string) error {
+	if pages != "" {
+		return fmt.Errorf("rotate PDF with PDFtk (page-specific rotation): %w", gotenberg.ErrPdfEngineMethodNotSupported)
+	}
+
+	var direction string
+	switch angle {
+	case 90:
+		direction = "east"
+	case 180:
+		direction = "south"
+	case 270:
+		direction = "west"
+	default:
+		return fmt.Errorf("rotate PDF with PDFtk: %w", gotenberg.ErrPdfRotateAngleNotSupported)
+	}
+
+	tmpPath := inputPath + ".tmp"
+	args := []string{inputPath, "cat", "1-end" + direction, "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("rotate 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

@@ -231,6 +231,11 @@ func (engine *QPdf) Stamp(ctx context.Context, logger *zap.Logger, inputPath str
 	return fmt.Errorf("stamp PDF with QPDF: %w", gotenberg.ErrPdfEngineMethodNotSupported)
 }
 
+// Rotate is not available in this implementation.
+func (engine *QPdf) Rotate(ctx context.Context, logger *zap.Logger, inputPath string, angle int, pages string) error {
+	return fmt.Errorf("rotate PDF with QPDF: %w", gotenberg.ErrPdfEngineMethodNotSupported)
+}
+
 var (
 	_ gotenberg.Module      = (*QPdf)(nil)
 	_ gotenberg.Provisioner = (*QPdf)(nil)

test/integration/features/chromium_convert_html.feature

@@ -1010,6 +1010,16 @@ Feature: /forms/chromium/convert/html
     Then the response header "Content-Type" should be "application/pdf"
     Then there should be 1 PDF(s) in the response
 
+  @rotate
+  Scenario: POST /forms/chromium/convert/html (Rotate 90)
+    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  |
+      | rotateAngle | 90                              | 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

test/integration/features/libreoffice_convert.feature

@@ -585,6 +585,16 @@ Feature: /forms/libreoffice/convert
     Then the response header "Content-Type" should be "application/pdf"
     Then there should be 1 PDF(s) in the response
 
+  @rotate
+  Scenario: POST /forms/libreoffice/convert (Rotate 90)
+    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  |
+      | rotateAngle | 90                   | 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
@@ -640,9 +650,10 @@ Feature: /forms/libreoffice/convert
   @metadata
   @watermark
   @stamp
+  @rotate
   @flatten
   @embed
-  Scenario: POST /forms/libreoffice/convert (PDF/A-3b & PDF/UA-1 & Metadata & Watermark & Stamp & Flatten & Embeds)
+  Scenario: POST /forms/libreoffice/convert (PDF/A-3b & PDF/UA-1 & Metadata & Watermark & Stamp & Rotate & 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   |
@@ -653,6 +664,7 @@ Feature: /forms/libreoffice/convert
       | watermarkExpression       | CONFIDENTIAL                                                                                                                                                                                                                                                                                              | field  |
       | stampSource               | text                                                                                                                                                                                                                                                                                                      | field  |
       | stampExpression           | DRAFT                                                                                                                                                                                                                                                                                                     | field  |
+      | rotateAngle               | 90                                                                                                                                                                                                                                                                                                        | field  |
       | flatten                   | true                                                                                                                                                                                                                                                                                                      | field  |
       | embeds                    | testdata/embed_1.xml                                                                                                                                                                                                                                                                                      | file   |
       | embeds                    | testdata/embed_2.xml                                                                                                                                                                                                                                                                                      | file   |

test/integration/features/pdfengines_merge.feature

@@ -425,6 +425,17 @@ Feature: /forms/pdfengines/merge
     Then the response header "Content-Type" should be "application/pdf"
     Then there should be 1 PDF(s) in the response
 
+  @rotate
+  Scenario: POST /forms/pdfengines/merge (Rotate 90)
+    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  |
+      | rotateAngle | 90                  | 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
@@ -443,10 +454,11 @@ Feature: /forms/pdfengines/merge
   @metadata
   @watermark
   @stamp
+  @rotate
   @flatten
   @embed
   @bookmarks
-  Scenario: POST /forms/pdfengines/merge (PDF/A-3b & PDF/UA-1 & Metadata & Watermark & Stamp & Flatten & Embeds & Bookmarks)
+  Scenario: POST /forms/pdfengines/merge (PDF/A-3b & PDF/UA-1 & Metadata & Watermark & Stamp & Rotate & 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   |
@@ -458,6 +470,7 @@ Feature: /forms/pdfengines/merge
       | watermarkExpression       | CONFIDENTIAL                                                                                                                                                                                                                                                                                              | field  |
       | stampSource               | text                                                                                                                                                                                                                                                                                                      | field  |
       | stampExpression           | DRAFT                                                                                                                                                                                                                                                                                                     | field  |
+      | rotateAngle               | 90                                                                                                                                                                                                                                                                                                        | field  |
       | bookmarks                 | [{"title":"Merged Index","page":1}]                                                                                                                                                                                                                                                                       | field  |
       | flatten                   | true                                                                                                                                                                                                                                                                                                      | field  |
       | embeds                    | testdata/embed_1.xml                                                                                                                                                                                                                                                                                      | file   |

test/integration/features/pdfengines_rotate.feature

@@ -0,0 +1,164 @@
+@pdfengines
+@pdfengines-rotate
+@rotate
+Feature: /forms/pdfengines/rotate
+
+  Scenario: POST /forms/pdfengines/rotate (90 - All Pages - pdfcpu)
+    Given I have a Gotenberg container with the following environment variable(s):
+      | PDFENGINES_ROTATE_ENGINES | pdfcpu |
+    When I make a "POST" request to Gotenberg at the "/forms/pdfengines/rotate" endpoint with the following form data and header(s):
+      | files       | testdata/pages_3.pdf | file  |
+      | rotateAngle | 90                   | 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/rotate (180 - All Pages - pdfcpu)
+    Given I have a Gotenberg container with the following environment variable(s):
+      | PDFENGINES_ROTATE_ENGINES | pdfcpu |
+    When I make a "POST" request to Gotenberg at the "/forms/pdfengines/rotate" endpoint with the following form data and header(s):
+      | files       | testdata/page_1.pdf | file  |
+      | rotateAngle | 180                 | 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/rotate (270 - All Pages - pdfcpu)
+    Given I have a Gotenberg container with the following environment variable(s):
+      | PDFENGINES_ROTATE_ENGINES | pdfcpu |
+    When I make a "POST" request to Gotenberg at the "/forms/pdfengines/rotate" endpoint with the following form data and header(s):
+      | files       | testdata/page_1.pdf | file  |
+      | rotateAngle | 270                 | 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/rotate (90 - Specific Pages - pdfcpu)
+    Given I have a Gotenberg container with the following environment variable(s):
+      | PDFENGINES_ROTATE_ENGINES | pdfcpu |
+    When I make a "POST" request to Gotenberg at the "/forms/pdfengines/rotate" endpoint with the following form data and header(s):
+      | files       | testdata/pages_3.pdf | file  |
+      | rotateAngle | 90                   | field |
+      | rotatePages | 1,3                  | 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/rotate (90 - All Pages - pdftk)
+    Given I have a Gotenberg container with the following environment variable(s):
+      | PDFENGINES_ROTATE_ENGINES | pdftk |
+    When I make a "POST" request to Gotenberg at the "/forms/pdfengines/rotate" endpoint with the following form data and header(s):
+      | files       | testdata/page_1.pdf | file  |
+      | rotateAngle | 90                  | 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/rotate (Specific Pages - pdftk unsupported)
+    Given I have a Gotenberg container with the following environment variable(s):
+      | PDFENGINES_ROTATE_ENGINES | pdftk |
+    When I make a "POST" request to Gotenberg at the "/forms/pdfengines/rotate" endpoint with the following form data and header(s):
+      | files       | testdata/pages_3.pdf | file  |
+      | rotateAngle | 90                   | field |
+      | rotatePages | 1,3                  | field |
+    Then the response status code should be 500
+
+  Scenario: POST /forms/pdfengines/rotate (Bad Request - Invalid Angle)
+    Given I have a default Gotenberg container
+    When I make a "POST" request to Gotenberg at the "/forms/pdfengines/rotate" endpoint with the following form data and header(s):
+      | files       | testdata/page_1.pdf | file  |
+      | rotateAngle | 45                  | field |
+    Then the response status code should be 400
+    Then the response body should contain string:
+      """
+      Invalid form data: form field 'rotateAngle' is invalid
+      """
+
+  Scenario: POST /forms/pdfengines/rotate (Bad Request - Missing Angle)
+    Given I have a default Gotenberg container
+    When I make a "POST" request to Gotenberg at the "/forms/pdfengines/rotate" 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 'rotateAngle' is required
+      """
+
+  Scenario: POST /forms/pdfengines/rotate (Bad Request - No PDF)
+    Given I have a default Gotenberg container
+    When I make a "POST" request to Gotenberg at the "/forms/pdfengines/rotate" endpoint with the following form data and header(s):
+      | rotateAngle | 90 | 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/rotate (Many PDFs)
+    Given I have a default Gotenberg container
+    When I make a "POST" request to Gotenberg at the "/forms/pdfengines/rotate" endpoint with the following form data and header(s):
+      | files       | testdata/page_1.pdf | file  |
+      | files       | testdata/page_2.pdf | file  |
+      | rotateAngle | 90                  | 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/rotate (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/rotate" endpoint with the following form data and header(s):
+      | files       | testdata/page_1.pdf | file  |
+      | rotateAngle | 90                  | field |
+    Then the response status code should be 404
+
+  Scenario: POST /forms/pdfengines/rotate (Gotenberg Trace)
+    Given I have a default Gotenberg container
+    When I make a "POST" request to Gotenberg at the "/forms/pdfengines/rotate" endpoint with the following form data and header(s):
+      | files           | testdata/page_1.pdf     | file   |
+      | rotateAngle     | 90                      | field  |
+      | Gotenberg-Trace | forms_pdfengines_rotate | 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_rotate"
+    Then the Gotenberg container should log the following entries:
+      | "trace":"forms_pdfengines_rotate" |
+
+  @webhook
+  Scenario: POST /forms/pdfengines/rotate (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/rotate" endpoint with the following form data and header(s):
+      | files                       | testdata/page_1.pdf                          | file   |
+      | rotateAngle                 | 90                                           | 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/rotate (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/rotate" endpoint with the following form data and header(s):
+      | files       | testdata/page_1.pdf | file  |
+      | rotateAngle | 90                  | field |
+    Then the response status code should be 401
+
+  Scenario: POST /foo/forms/pdfengines/rotate (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/rotate" endpoint with the following form data and header(s):
+      | files       | testdata/page_1.pdf | file  |
+      | rotateAngle | 90                  | field |
+    Then the response status code should be 200
+    Then the response header "Content-Type" should be "application/pdf"

test/integration/features/pdfengines_split.feature

@@ -499,6 +499,18 @@ Feature: /forms/pdfengines/split
     Then the response header "Content-Type" should be "application/zip"
     Then there should be 2 PDF(s) in the response
 
+  @rotate
+  Scenario: POST /forms/pdfengines/split (Rotate 90)
+    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 |
+      | rotateAngle | 90                   | 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
@@ -522,9 +534,10 @@ Feature: /forms/pdfengines/split
   @metadata
   @watermark
   @stamp
+  @rotate
   @flatten
   @embed
-  Scenario: POST /forms/pdfengines/split (PDF/A-3b & PDF/UA-1 & Metadata & Watermark & Stamp & Flatten & Embeds)
+  Scenario: POST /forms/pdfengines/split (PDF/A-3b & PDF/UA-1 & Metadata & Watermark & Stamp & Rotate & 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  |
@@ -537,6 +550,7 @@ Feature: /forms/pdfengines/split
       | watermarkExpression | CONFIDENTIAL                                                                                                                                                                                                                                                                                              | field |
       | stampSource         | text                                                                                                                                                                                                                                                                                                      | field |
       | stampExpression     | DRAFT                                                                                                                                                                                                                                                                                                     | field |
+      | rotateAngle         | 90                                                                                                                                                                                                                                                                                                        | field |
       | flatten             | true                                                                                                                                                                                                                                                                                                      | field |
       | embeds              | testdata/embed_1.xml                                                                                                                                                                                                                                                                                      | file  |
       | embeds              | testdata/embed_2.xml                                                                                                                                                                                                                                                                                      | file  |