From 8f74e7d3317a6d87876daa7b8757641992749c7d Mon Sep 17 00:00:00 2001
From: Alex <64072843+A1ex3@users.noreply.github.com>
Date: Tue, 4 Nov 2025 21:50:56 +0700
Subject: [PATCH] backend/compress: add zstd compression

Added support for reading and writing zstd-compressed archives in seekable format
using "github.com/klauspost/compress/zstd" and
"github.com/SaveTheRbtz/zstd-seekable-format-go/pkg".

Bumped Go version from 1.24.0 to 1.24.4 due to requirements of
"github.com/SaveTheRbtz/zstd-seekable-format-go/pkg".
---
 backend/compress/compress.go             | 318 +++++++++-------------
 backend/compress/compress_test.go        |  22 +-
 backend/compress/gzip_handler.go         | 207 ++++++++++++++
 backend/compress/szstd_helper.go         | 327 +++++++++++++++++++++++
 backend/compress/uncompressed_handler.go |  65 +++++
 backend/compress/unknown_handler.go      |  65 +++++
 backend/compress/zstd_handler.go         | 192 +++++++++++++
 docs/content/compress.md                 | 114 +++++---
 fstest/test_all/config.yaml              |   3 +
 go.mod                                   |   4 +-
 go.sum                                   |   4 +
 11 files changed, 1093 insertions(+), 228 deletions(-)
 create mode 100644 backend/compress/gzip_handler.go
 create mode 100644 backend/compress/szstd_helper.go
 create mode 100644 backend/compress/uncompressed_handler.go
 create mode 100644 backend/compress/unknown_handler.go
 create mode 100644 backend/compress/zstd_handler.go

diff --git a/backend/compress/compress.go b/backend/compress/compress.go
index 0cc56bc62..961d3898f 100644
--- a/backend/compress/compress.go
+++ b/backend/compress/compress.go
@@ -2,10 +2,8 @@
 package compress
 
 import (
-	"bufio"
 	"bytes"
 	"context"
-	"crypto/md5"
 	"encoding/base64"
 	"encoding/binary"
 	"encoding/hex"
@@ -46,6 +44,7 @@ const (
 	minCompressionRatio = 1.1
 
 	gzFileExt           = ".gz"
+	zstdFileExt         = ".zst"
 	metaFileExt         = ".json"
 	uncompressedFileExt = ".bin"
 )
@@ -54,6 +53,7 @@ const (
 const (
 	Uncompressed = 0
 	Gzip         = 2
+	Zstd         = 4
 )
 
 var nameRegexp = regexp.MustCompile(`^(.+?)\.([A-Za-z0-9-_]{11})$`)
@@ -66,6 +66,10 @@ func init() {
 			Value: "gzip",
 			Help:  "Standard gzip compression with fastest parameters.",
 		},
+		{
+			Value: "zstd",
+			Help:  "Zstandard compression — fast modern algorithm offering adjustable speed-to-compression tradeoffs.",
+		},
 	}
 
 	// Register our remote
@@ -87,17 +91,23 @@ func init() {
 			Examples: compressionModeOptions,
 		}, {
 			Name: "level",
-			Help: `GZIP compression level (-2 to 9).
-
-Generally -1 (default, equivalent to 5) is recommended.
-Levels 1 to 9 increase compression at the cost of speed. Going past 6 
-generally offers very little return.
-
-Level -2 uses Huffman encoding only. Only use if you know what you
-are doing.
-Level 0 turns off compression.`,
-			Default:  sgzip.DefaultCompression,
-			Advanced: true,
+			Help: `GZIP (levels -2 to 9):
+- -2 — Huffman encoding only. Only use if you know what you're doing.
+- -1 (default) — recommended; equivalent to level 5.
+- 0 — turns off compression.
+- 1–9 — increase compression at the cost of speed. Going past 6 generally offers very little return.
+ 
+ZSTD (levels 0 to 4):
+- 0 — turns off compression entirely.
+- 1 — fastest compression with the lowest ratio.
+- 2 (default) — good balance of speed and compression.
+- 3 — better compression, but uses about 2–3x more CPU than the default.
+- 4 — best possible compression ratio (highest CPU cost).
+ 
+Notes:
+- Choose GZIP for wide compatibility; ZSTD for better speed/ratio tradeoffs.
+- Negative gzip levels: -2 = Huffman-only, -1 = default (≈ level 5).`,
+			Required: true,
 		}, {
 			Name: "ram_cache_limit",
 			Help: `Some remotes don't allow the upload of files with unknown size.
@@ -112,6 +122,47 @@ this limit will be cached on disk.`,
 	})
 }
 
+// compressionModeHandler defines the interface for handling different compression modes
+type compressionModeHandler interface {
+	// processFileNameGetFileExtension returns the file extension for the given compression mode
+	processFileNameGetFileExtension(compressionMode int) string
+
+	// newObjectGetOriginalSize returns the original file size from the metadata
+	newObjectGetOriginalSize(meta *ObjectMetadata) (int64, error)
+
+	// isCompressible checks the compression ratio of the provided data and returns true if the ratio exceeds
+	// the configured threshold
+	isCompressible(r io.Reader, compressionMode int) (bool, error)
+
+	// putCompress compresses the input data and uploads it to the remote, returning the new object and its metadata
+	putCompress(
+		ctx context.Context,
+		f *Fs,
+		in io.Reader,
+		src fs.ObjectInfo,
+		options []fs.OpenOption,
+		mimeType string,
+	) (fs.Object, *ObjectMetadata, error)
+
+	// openGetReadCloser opens a compressed object and returns a ReadCloser in the Open method
+	openGetReadCloser(
+		ctx context.Context,
+		o *Object,
+		offset int64,
+		limit int64,
+		cr chunkedreader.ChunkedReader,
+		closer io.Closer,
+		options ...fs.OpenOption,
+	) (rc io.ReadCloser, err error)
+
+	// putUncompressGetNewMetadata returns metadata in the putUncompress method for a specific compression algorithm
+	putUncompressGetNewMetadata(o fs.Object, mode int, md5 string, mimeType string, sum []byte) (fs.Object, *ObjectMetadata, error)
+
+	// This function generates a metadata object for sgzip.GzipMetadata or SzstdMetadata.
+	// Warning: This function panics if cmeta is not of the expected type.
+	newMetadata(size int64, mode int, cmeta any, md5 string, mimeType string) *ObjectMetadata
+}
+
 // Options defines the configuration for this backend
 type Options struct {
 	Remote           string        `config:"remote"`
@@ -125,12 +176,13 @@ type Options struct {
 // Fs represents a wrapped fs.Fs
 type Fs struct {
 	fs.Fs
-	wrapper  fs.Fs
-	name     string
-	root     string
-	opt      Options
-	mode     int          // compression mode id
-	features *fs.Features // optional features
+	wrapper     fs.Fs
+	name        string
+	root        string
+	opt         Options
+	mode        int                    // compression mode id
+	features    *fs.Features           // optional features
+	modeHandler compressionModeHandler // compression mode handler
 }
 
 // NewFs constructs an Fs from the path, container:path
@@ -167,13 +219,28 @@ func NewFs(ctx context.Context, name, rpath string, m configmap.Mapper) (fs.Fs,
 		return nil, fmt.Errorf("failed to make remote %s:%q to wrap: %w", wName, remotePath, err)
 	}
 
+	compressionMode := compressionModeFromName(opt.CompressionMode)
+	var modeHandler compressionModeHandler
+
+	switch compressionMode {
+	case Gzip:
+		modeHandler = &gzipModeHandler{}
+	case Zstd:
+		modeHandler = &zstdModeHandler{}
+	case Uncompressed:
+		modeHandler = &uncompressedModeHandler{}
+	default:
+		modeHandler = &unknownModeHandler{}
+	}
+
 	// Create the wrapping fs
 	f := &Fs{
-		Fs:   wrappedFs,
-		name: name,
-		root: rpath,
-		opt:  *opt,
-		mode: compressionModeFromName(opt.CompressionMode),
+		Fs:          wrappedFs,
+		name:        name,
+		root:        rpath,
+		opt:         *opt,
+		mode:        compressionMode,
+		modeHandler: modeHandler,
 	}
 	// Correct root if definitely pointing to a file
 	if err == fs.ErrorIsFile {
@@ -215,10 +282,13 @@ func NewFs(ctx context.Context, name, rpath string, m configmap.Mapper) (fs.Fs,
 	return f, err
 }
 
+// compressionModeFromName converts a compression mode name to its int representation.
 func compressionModeFromName(name string) int {
 	switch name {
 	case "gzip":
 		return Gzip
+	case "zstd":
+		return Zstd
 	default:
 		return Uncompressed
 	}
@@ -242,7 +312,7 @@ func base64ToInt64(str string) (int64, error) {
 
 // Processes a file name for a compressed file. Returns the original file name, the extension, and the size of the original file.
 // Returns -2 for the original size if the file is uncompressed.
-func processFileName(compressedFileName string) (origFileName string, extension string, origSize int64, err error) {
+func processFileName(compressedFileName string, modeHandler compressionModeHandler) (origFileName string, extension string, origSize int64, err error) {
 	// Separate the filename and size from the extension
 	extensionPos := strings.LastIndex(compressedFileName, ".")
 	if extensionPos == -1 {
@@ -261,7 +331,8 @@ func processFileName(compressedFileName string) (origFileName string, extension
 	if err != nil {
 		return "", "", 0, errors.New("could not decode size")
 	}
-	return match[1], gzFileExt, size, nil
+	ext := modeHandler.processFileNameGetFileExtension(compressionModeFromName(compressedFileName[extensionPos+1:]))
+	return match[1], ext, size, nil
 }
 
 // Generates the file name for a metadata file
@@ -286,11 +357,15 @@ func unwrapMetadataFile(filename string) (string, bool) {
 
 // makeDataName generates the file name for a data file with specified compression mode
 func makeDataName(remote string, size int64, mode int) (newRemote string) {
-	if mode != Uncompressed {
+	switch mode {
+	case Gzip:
 		newRemote = remote + "." + int64ToBase64(size) + gzFileExt
-	} else {
+	case Zstd:
+		newRemote = remote + "." + int64ToBase64(size) + zstdFileExt
+	default:
 		newRemote = remote + uncompressedFileExt
 	}
+
 	return newRemote
 }
 
@@ -304,7 +379,7 @@ func (f *Fs) dataName(remote string, size int64, compressed bool) (name string)
 
 // addData parses an object and adds it to the DirEntries
 func (f *Fs) addData(entries *fs.DirEntries, o fs.Object) {
-	origFileName, _, size, err := processFileName(o.Remote())
+	origFileName, _, size, err := processFileName(o.Remote(), f.modeHandler)
 	if err != nil {
 		fs.Errorf(o, "Error on parsing file name: %v", err)
 		return
@@ -427,8 +502,12 @@ func (f *Fs) NewObject(ctx context.Context, remote string) (fs.Object, error) {
 	if err != nil {
 		return nil, fmt.Errorf("error decoding metadata: %w", err)
 	}
+	size, err := f.modeHandler.newObjectGetOriginalSize(meta)
+	if err != nil {
+		return nil, fmt.Errorf("error reading metadata: %w", err)
+	}
 	// Create our Object
-	o, err := f.Fs.NewObject(ctx, makeDataName(remote, meta.CompressionMetadata.Size, meta.Mode))
+	o, err := f.Fs.NewObject(ctx, makeDataName(remote, size, meta.Mode))
 	if err != nil {
 		return nil, err
 	}
@@ -437,7 +516,7 @@ func (f *Fs) NewObject(ctx context.Context, remote string) (fs.Object, error) {
 
 // checkCompressAndType checks if an object is compressible and determines it's mime type
 // returns a multireader with the bytes that were read to determine mime type
-func checkCompressAndType(in io.Reader) (newReader io.Reader, compressible bool, mimeType string, err error) {
+func checkCompressAndType(in io.Reader, compressionMode int, modeHandler compressionModeHandler) (newReader io.Reader, compressible bool, mimeType string, err error) {
 	in, wrap := accounting.UnWrap(in)
 	buf := make([]byte, heuristicBytes)
 	n, err := in.Read(buf)
@@ -446,7 +525,7 @@ func checkCompressAndType(in io.Reader) (newReader io.Reader, compressible bool,
 		return nil, false, "", err
 	}
 	mime := mimetype.Detect(buf)
-	compressible, err = isCompressible(bytes.NewReader(buf))
+	compressible, err = modeHandler.isCompressible(bytes.NewReader(buf), compressionMode)
 	if err != nil {
 		return nil, false, "", err
 	}
@@ -454,26 +533,6 @@ func checkCompressAndType(in io.Reader) (newReader io.Reader, compressible bool,
 	return wrap(in), compressible, mime.String(), nil
 }
 
-// isCompressible checks the compression ratio of the provided data and returns true if the ratio exceeds
-// the configured threshold
-func isCompressible(r io.Reader) (bool, error) {
-	var b bytes.Buffer
-	w, err := sgzip.NewWriterLevel(&b, sgzip.DefaultCompression)
-	if err != nil {
-		return false, err
-	}
-	n, err := io.Copy(w, r)
-	if err != nil {
-		return false, err
-	}
-	err = w.Close()
-	if err != nil {
-		return false, err
-	}
-	ratio := float64(n) / float64(b.Len())
-	return ratio > minCompressionRatio, nil
-}
-
 // verifyObjectHash verifies the Objects hash
 func (f *Fs) verifyObjectHash(ctx context.Context, o fs.Object, hasher *hash.MultiHasher, ht hash.Type) error {
 	srcHash := hasher.Sums()[ht]
@@ -494,9 +553,9 @@ func (f *Fs) verifyObjectHash(ctx context.Context, o fs.Object, hasher *hash.Mul
 
 type putFn func(ctx context.Context, in io.Reader, src fs.ObjectInfo, options ...fs.OpenOption) (fs.Object, error)
 
-type compressionResult struct {
+type compressionResult[T sgzip.GzipMetadata | SzstdMetadata] struct {
 	err  error
-	meta sgzip.GzipMetadata
+	meta T
 }
 
 // replicating some of operations.Rcat functionality because we want to support remotes without streaming
@@ -537,106 +596,18 @@ func (f *Fs) rcat(ctx context.Context, dstFileName string, in io.ReadCloser, mod
 		return nil, fmt.Errorf("failed to write temporary local file: %w", err)
 	}
 	if _, err = tempFile.Seek(0, 0); err != nil {
-		return nil, err
+		return nil, fmt.Errorf("failed to seek temporary local file: %w", err)
 	}
 	finfo, err := tempFile.Stat()
 	if err != nil {
-		return nil, err
+		return nil, fmt.Errorf("failed to stat temporary local file: %w", err)
 	}
 	return f.Fs.Put(ctx, tempFile, object.NewStaticObjectInfo(dstFileName, modTime, finfo.Size(), false, nil, f.Fs))
 }
 
 // Put a compressed version of a file. Returns a wrappable object and metadata.
 func (f *Fs) putCompress(ctx context.Context, in io.Reader, src fs.ObjectInfo, options []fs.OpenOption, mimeType string) (fs.Object, *ObjectMetadata, error) {
-	// Unwrap reader accounting
-	in, wrap := accounting.UnWrap(in)
-
-	// Add the metadata hasher
-	metaHasher := md5.New()
-	in = io.TeeReader(in, metaHasher)
-
-	// Compress the file
-	pipeReader, pipeWriter := io.Pipe()
-	results := make(chan compressionResult)
-	go func() {
-		gz, err := sgzip.NewWriterLevel(pipeWriter, f.opt.CompressionLevel)
-		if err != nil {
-			results <- compressionResult{err: err, meta: sgzip.GzipMetadata{}}
-			return
-		}
-		_, err = io.Copy(gz, in)
-		gzErr := gz.Close()
-		if gzErr != nil {
-			fs.Errorf(nil, "Failed to close compress: %v", gzErr)
-			if err == nil {
-				err = gzErr
-			}
-		}
-		closeErr := pipeWriter.Close()
-		if closeErr != nil {
-			fs.Errorf(nil, "Failed to close pipe: %v", closeErr)
-			if err == nil {
-				err = closeErr
-			}
-		}
-		results <- compressionResult{err: err, meta: gz.MetaData()}
-	}()
-	wrappedIn := wrap(bufio.NewReaderSize(pipeReader, bufferSize)) // Probably no longer needed as sgzip has it's own buffering
-
-	// Find a hash the destination supports to compute a hash of
-	// the compressed data.
-	ht := f.Fs.Hashes().GetOne()
-	var hasher *hash.MultiHasher
-	var err error
-	if ht != hash.None {
-		// unwrap the accounting again
-		wrappedIn, wrap = accounting.UnWrap(wrappedIn)
-		hasher, err = hash.NewMultiHasherTypes(hash.NewHashSet(ht))
-		if err != nil {
-			return nil, nil, err
-		}
-		// add the hasher and re-wrap the accounting
-		wrappedIn = io.TeeReader(wrappedIn, hasher)
-		wrappedIn = wrap(wrappedIn)
-	}
-
-	// Transfer the data
-	o, err := f.rcat(ctx, makeDataName(src.Remote(), src.Size(), f.mode), io.NopCloser(wrappedIn), src.ModTime(ctx), options)
-	//o, err := operations.Rcat(ctx, f.Fs, makeDataName(src.Remote(), src.Size(), f.mode), io.NopCloser(wrappedIn), src.ModTime(ctx))
-	if err != nil {
-		if o != nil {
-			removeErr := o.Remove(ctx)
-			if removeErr != nil {
-				fs.Errorf(o, "Failed to remove partially transferred object: %v", err)
-			}
-		}
-		return nil, nil, err
-	}
-	// Check whether we got an error during compression
-	result := <-results
-	err = result.err
-	if err != nil {
-		if o != nil {
-			removeErr := o.Remove(ctx)
-			if removeErr != nil {
-				fs.Errorf(o, "Failed to remove partially compressed object: %v", err)
-			}
-		}
-		return nil, nil, err
-	}
-
-	// Generate metadata
-	meta := newMetadata(result.meta.Size, f.mode, result.meta, hex.EncodeToString(metaHasher.Sum(nil)), mimeType)
-
-	// Check the hashes of the compressed data if we were comparing them
-	if ht != hash.None && hasher != nil {
-		err = f.verifyObjectHash(ctx, o, hasher, ht)
-		if err != nil {
-			return nil, nil, err
-		}
-	}
-
-	return o, meta, nil
+	return f.modeHandler.putCompress(ctx, f, in, src, options, mimeType)
 }
 
 // Put an uncompressed version of a file. Returns a wrappable object and metadata.
@@ -680,7 +651,8 @@ func (f *Fs) putUncompress(ctx context.Context, in io.Reader, src fs.ObjectInfo,
 	if err != nil {
 		return nil, nil, err
 	}
-	return o, newMetadata(o.Size(), Uncompressed, sgzip.GzipMetadata{}, hex.EncodeToString(sum), mimeType), nil
+
+	return f.modeHandler.putUncompressGetNewMetadata(o, Uncompressed, hex.EncodeToString(sum), mimeType, sum)
 }
 
 // This function will write a metadata struct to a metadata Object for an src. Returns a wrappable metadata object.
@@ -751,7 +723,7 @@ func (f *Fs) Put(ctx context.Context, in io.Reader, src fs.ObjectInfo, options .
 	o, err := f.NewObject(ctx, src.Remote())
 	if err == fs.ErrorObjectNotFound {
 		// Get our file compressibility
-		in, compressible, mimeType, err := checkCompressAndType(in)
+		in, compressible, mimeType, err := checkCompressAndType(in, f.mode, f.modeHandler)
 		if err != nil {
 			return nil, err
 		}
@@ -771,7 +743,7 @@ func (f *Fs) PutStream(ctx context.Context, in io.Reader, src fs.ObjectInfo, opt
 	}
 	found := err == nil
 
-	in, compressible, mimeType, err := checkCompressAndType(in)
+	in, compressible, mimeType, err := checkCompressAndType(in, f.mode, f.modeHandler)
 	if err != nil {
 		return nil, err
 	}
@@ -1090,11 +1062,12 @@ func (f *Fs) PublicLink(ctx context.Context, remote string, duration fs.Duration
 
 // ObjectMetadata describes the metadata for an Object.
 type ObjectMetadata struct {
-	Mode                int    // Compression mode of the file.
-	Size                int64  // Size of the object.
-	MD5                 string // MD5 hash of the file.
-	MimeType            string // Mime type of the file
-	CompressionMetadata sgzip.GzipMetadata
+	Mode                    int                 // Compression mode of the file.
+	Size                    int64               // Size of the object.
+	MD5                     string              // MD5 hash of the file.
+	MimeType                string              // Mime type of the file
+	CompressionMetadataGzip *sgzip.GzipMetadata // Metadata for Gzip compression
+	CompressionMetadataZstd *SzstdMetadata      // Metadata for Zstd compression
 }
 
 // Object with external metadata
@@ -1107,17 +1080,6 @@ type Object struct {
 	meta      *ObjectMetadata // Metadata struct for this object (nil if not loaded)
 }
 
-// This function generates a metadata object
-func newMetadata(size int64, mode int, cmeta sgzip.GzipMetadata, md5 string, mimeType string) *ObjectMetadata {
-	meta := new(ObjectMetadata)
-	meta.Size = size
-	meta.Mode = mode
-	meta.CompressionMetadata = cmeta
-	meta.MD5 = md5
-	meta.MimeType = mimeType
-	return meta
-}
-
 // This function will read the metadata from a metadata object.
 func readMetadata(ctx context.Context, mo fs.Object) (meta *ObjectMetadata, err error) {
 	// Open our meradata object
@@ -1165,7 +1127,7 @@ func (o *Object) Update(ctx context.Context, in io.Reader, src fs.ObjectInfo, op
 		return o.mo, o.mo.Update(ctx, in, src, options...)
 	}
 
-	in, compressible, mimeType, err := checkCompressAndType(in)
+	in, compressible, mimeType, err := checkCompressAndType(in, o.meta.Mode, o.f.modeHandler)
 	if err != nil {
 		return err
 	}
@@ -1278,7 +1240,7 @@ func (o *Object) String() string {
 
 // Remote returns the remote path
 func (o *Object) Remote() string {
-	origFileName, _, _, err := processFileName(o.Object.Remote())
+	origFileName, _, _, err := processFileName(o.Object.Remote(), o.f.modeHandler)
 	if err != nil {
 		fs.Errorf(o.f, "Could not get remote path for: %s", o.Object.Remote())
 		return o.Object.Remote()
@@ -1381,7 +1343,6 @@ func (o *Object) Open(ctx context.Context, options ...fs.OpenOption) (rc io.Read
 		return o.Object.Open(ctx, options...)
 	}
 	// Get offset and limit from OpenOptions, pass the rest to the underlying remote
-	var openOptions = []fs.OpenOption{&fs.SeekOption{Offset: 0}}
 	var offset, limit int64 = 0, -1
 	for _, option := range options {
 		switch x := option.(type) {
@@ -1389,31 +1350,12 @@ func (o *Object) Open(ctx context.Context, options ...fs.OpenOption) (rc io.Read
 			offset = x.Offset
 		case *fs.RangeOption:
 			offset, limit = x.Decode(o.Size())
-		default:
-			openOptions = append(openOptions, option)
 		}
 	}
 	// Get a chunkedreader for the wrapped object
 	chunkedReader := chunkedreader.New(ctx, o.Object, initialChunkSize, maxChunkSize, chunkStreams)
-	// Get file handle
-	var file io.Reader
-	if offset != 0 {
-		file, err = sgzip.NewReaderAt(chunkedReader, &o.meta.CompressionMetadata, offset)
-	} else {
-		file, err = sgzip.NewReader(chunkedReader)
-	}
-	if err != nil {
-		return nil, err
-	}
-
-	var fileReader io.Reader
-	if limit != -1 {
-		fileReader = io.LimitReader(file, limit)
-	} else {
-		fileReader = file
-	}
-	// Return a ReadCloser
-	return ReadCloserWrapper{Reader: fileReader, Closer: chunkedReader}, nil
+	var retCloser io.Closer = chunkedReader
+	return o.f.modeHandler.openGetReadCloser(ctx, o, offset, limit, chunkedReader, retCloser, options...)
 }
 
 // ObjectInfo describes a wrapped fs.ObjectInfo for being the source
diff --git a/backend/compress/compress_test.go b/backend/compress/compress_test.go
index 8fc954dfa..000d70330 100644
--- a/backend/compress/compress_test.go
+++ b/backend/compress/compress_test.go
@@ -48,7 +48,27 @@ func TestRemoteGzip(t *testing.T) {
 	opt.ExtraConfig = []fstests.ExtraConfigItem{
 		{Name: name, Key: "type", Value: "compress"},
 		{Name: name, Key: "remote", Value: tempdir},
-		{Name: name, Key: "compression_mode", Value: "gzip"},
+		{Name: name, Key: "mode", Value: "gzip"},
+		{Name: name, Key: "level", Value: "-1"},
+	}
+	opt.QuickTestOK = true
+	fstests.Run(t, &opt)
+}
+
+// TestRemoteZstd tests ZSTD compression
+func TestRemoteZstd(t *testing.T) {
+	if *fstest.RemoteName != "" {
+		t.Skip("Skipping as -remote set")
+	}
+	tempdir := filepath.Join(os.TempDir(), "rclone-compress-test-zstd")
+	name := "TestCompressZstd"
+	opt := defaultOpt
+	opt.RemoteName = name + ":"
+	opt.ExtraConfig = []fstests.ExtraConfigItem{
+		{Name: name, Key: "type", Value: "compress"},
+		{Name: name, Key: "remote", Value: tempdir},
+		{Name: name, Key: "mode", Value: "zstd"},
+		{Name: name, Key: "level", Value: "2"},
 	}
 	opt.QuickTestOK = true
 	fstests.Run(t, &opt)
diff --git a/backend/compress/gzip_handler.go b/backend/compress/gzip_handler.go
new file mode 100644
index 000000000..a5abbf7c8
--- /dev/null
+++ b/backend/compress/gzip_handler.go
@@ -0,0 +1,207 @@
+package compress
+
+import (
+	"bufio"
+	"bytes"
+	"context"
+	"crypto/md5"
+	"encoding/hex"
+	"errors"
+	"io"
+
+	"github.com/buengese/sgzip"
+
+	"github.com/rclone/rclone/fs"
+	"github.com/rclone/rclone/fs/accounting"
+	"github.com/rclone/rclone/fs/chunkedreader"
+	"github.com/rclone/rclone/fs/hash"
+)
+
+// gzipModeHandler implements compressionModeHandler for gzip
+type gzipModeHandler struct{}
+
+// isCompressible checks the compression ratio of the provided data and returns true if the ratio exceeds
+// the configured threshold
+func (g *gzipModeHandler) isCompressible(r io.Reader, compressionMode int) (bool, error) {
+	var b bytes.Buffer
+	var n int64
+	w, err := sgzip.NewWriterLevel(&b, sgzip.DefaultCompression)
+	if err != nil {
+		return false, err
+	}
+	n, err = io.Copy(w, r)
+	if err != nil {
+		return false, err
+	}
+	err = w.Close()
+	if err != nil {
+		return false, err
+	}
+	ratio := float64(n) / float64(b.Len())
+	return ratio > minCompressionRatio, nil
+}
+
+// newObjectGetOriginalSize returns the original file size from the metadata
+func (g *gzipModeHandler) newObjectGetOriginalSize(meta *ObjectMetadata) (int64, error) {
+	if meta.CompressionMetadataGzip == nil {
+		return 0, errors.New("missing gzip metadata")
+	}
+	return meta.CompressionMetadataGzip.Size, nil
+}
+
+// openGetReadCloser opens a compressed object and returns a ReadCloser in the Open method
+func (g *gzipModeHandler) openGetReadCloser(
+	ctx context.Context,
+	o *Object,
+	offset int64,
+	limit int64,
+	cr chunkedreader.ChunkedReader,
+	closer io.Closer,
+	options ...fs.OpenOption,
+) (rc io.ReadCloser, err error) {
+	var file io.Reader
+
+	if offset != 0 {
+		file, err = sgzip.NewReaderAt(cr, o.meta.CompressionMetadataGzip, offset)
+	} else {
+		file, err = sgzip.NewReader(cr)
+	}
+	if err != nil {
+		return nil, err
+	}
+
+	var fileReader io.Reader
+	if limit != -1 {
+		fileReader = io.LimitReader(file, limit)
+	} else {
+		fileReader = file
+	}
+	// Return a ReadCloser
+	return ReadCloserWrapper{Reader: fileReader, Closer: closer}, nil
+}
+
+// processFileNameGetFileExtension returns the file extension for the given compression mode
+func (g *gzipModeHandler) processFileNameGetFileExtension(compressionMode int) string {
+	if compressionMode == Gzip {
+		return gzFileExt
+	}
+
+	return ""
+}
+
+// putCompress compresses the input data and uploads it to the remote, returning the new object and its metadata
+func (g *gzipModeHandler) putCompress(
+	ctx context.Context,
+	f *Fs,
+	in io.Reader,
+	src fs.ObjectInfo,
+	options []fs.OpenOption,
+	mimeType string,
+) (fs.Object, *ObjectMetadata, error) {
+	// Unwrap reader accounting
+	in, wrap := accounting.UnWrap(in)
+
+	// Add the metadata hasher
+	metaHasher := md5.New()
+	in = io.TeeReader(in, metaHasher)
+
+	// Compress the file
+	pipeReader, pipeWriter := io.Pipe()
+
+	resultsGzip := make(chan compressionResult[sgzip.GzipMetadata])
+	go func() {
+		gz, err := sgzip.NewWriterLevel(pipeWriter, f.opt.CompressionLevel)
+		if err != nil {
+			resultsGzip <- compressionResult[sgzip.GzipMetadata]{err: err, meta: sgzip.GzipMetadata{}}
+			close(resultsGzip)
+			return
+		}
+		_, err = io.Copy(gz, in)
+		gzErr := gz.Close()
+		if gzErr != nil && err == nil {
+			err = gzErr
+		}
+		closeErr := pipeWriter.Close()
+		if closeErr != nil && err == nil {
+			err = closeErr
+		}
+		resultsGzip <- compressionResult[sgzip.GzipMetadata]{err: err, meta: gz.MetaData()}
+		close(resultsGzip)
+	}()
+
+	wrappedIn := wrap(bufio.NewReaderSize(pipeReader, bufferSize)) // Probably no longer needed as sgzip has it's own buffering
+
+	// Find a hash the destination supports to compute a hash of
+	// the compressed data.
+	ht := f.Fs.Hashes().GetOne()
+	var hasher *hash.MultiHasher
+	var err error
+	if ht != hash.None {
+		// unwrap the accounting again
+		wrappedIn, wrap = accounting.UnWrap(wrappedIn)
+		hasher, err = hash.NewMultiHasherTypes(hash.NewHashSet(ht))
+		if err != nil {
+			return nil, nil, err
+		}
+		// add the hasher and re-wrap the accounting
+		wrappedIn = io.TeeReader(wrappedIn, hasher)
+		wrappedIn = wrap(wrappedIn)
+	}
+
+	// Transfer the data
+	o, err := f.rcat(ctx, makeDataName(src.Remote(), src.Size(), f.mode), io.NopCloser(wrappedIn), src.ModTime(ctx), options)
+	if err != nil {
+		if o != nil {
+			if removeErr := o.Remove(ctx); removeErr != nil {
+				fs.Errorf(o, "Failed to remove partially transferred object: %v", removeErr)
+			}
+		}
+		return nil, nil, err
+	}
+	// Check whether we got an error during compression
+	result := <-resultsGzip
+	if result.err != nil {
+		if o != nil {
+			if removeErr := o.Remove(ctx); removeErr != nil {
+				fs.Errorf(o, "Failed to remove partially compressed object: %v", removeErr)
+			}
+		}
+		return nil, nil, result.err
+	}
+
+	// Generate metadata
+	meta := g.newMetadata(result.meta.Size, f.mode, result.meta, hex.EncodeToString(metaHasher.Sum(nil)), mimeType)
+
+	// Check the hashes of the compressed data if we were comparing them
+	if ht != hash.None && hasher != nil {
+		err = f.verifyObjectHash(ctx, o, hasher, ht)
+		if err != nil {
+			return nil, nil, err
+		}
+	}
+	return o, meta, nil
+}
+
+// putUncompressGetNewMetadata returns metadata in the putUncompress method for a specific compression algorithm
+func (g *gzipModeHandler) putUncompressGetNewMetadata(o fs.Object, mode int, md5 string, mimeType string, sum []byte) (fs.Object, *ObjectMetadata, error) {
+	return o, g.newMetadata(o.Size(), mode, sgzip.GzipMetadata{}, hex.EncodeToString(sum), mimeType), nil
+}
+
+// This function generates a metadata object for sgzip.GzipMetadata or SzstdMetadata.
+// Warning: This function panics if cmeta is not of the expected type.
+func (g *gzipModeHandler) newMetadata(size int64, mode int, cmeta any, md5 string, mimeType string) *ObjectMetadata {
+	meta, ok := cmeta.(sgzip.GzipMetadata)
+	if !ok {
+		panic("invalid cmeta type: expected sgzip.GzipMetadata")
+	}
+
+	objMeta := new(ObjectMetadata)
+	objMeta.Size = size
+	objMeta.Mode = mode
+	objMeta.CompressionMetadataGzip = &meta
+	objMeta.CompressionMetadataZstd = nil
+	objMeta.MD5 = md5
+	objMeta.MimeType = mimeType
+
+	return objMeta
+}
diff --git a/backend/compress/szstd_helper.go b/backend/compress/szstd_helper.go
new file mode 100644
index 000000000..97f591f5f
--- /dev/null
+++ b/backend/compress/szstd_helper.go
@@ -0,0 +1,327 @@
+package compress
+
+import (
+	"context"
+	"errors"
+	"io"
+	"runtime"
+	"sync"
+
+	szstd "github.com/a1ex3/zstd-seekable-format-go/pkg"
+	"github.com/klauspost/compress/zstd"
+)
+
+const szstdChunkSize int = 1 << 20 // 1 MiB chunk size
+
+// SzstdMetadata holds metadata for szstd compressed files.
+type SzstdMetadata struct {
+	BlockSize int      // BlockSize is the size of the blocks in the zstd file
+	Size      int64    // Size is the uncompressed size of the file
+	BlockData []uint32 // BlockData is the block data for the zstd file, used for seeking
+}
+
+// SzstdWriter is a writer that compresses data in szstd format.
+type SzstdWriter struct {
+	enc      *zstd.Encoder
+	w        szstd.ConcurrentWriter
+	metadata SzstdMetadata
+	mu       sync.Mutex
+}
+
+// NewWriterSzstd creates a new szstd writer with the specified options.
+// It initializes the szstd writer with a zstd encoder and returns a pointer to the SzstdWriter.
+// The writer can be used to write data in chunks, and it will automatically handle block sizes and metadata.
+func NewWriterSzstd(w io.Writer, opts ...zstd.EOption) (*SzstdWriter, error) {
+	encoder, err := zstd.NewWriter(nil, opts...)
+	if err != nil {
+		return nil, err
+	}
+
+	sw, err := szstd.NewWriter(w, encoder)
+	if err != nil {
+		if err := encoder.Close(); err != nil {
+			return nil, err
+		}
+		return nil, err
+	}
+
+	return &SzstdWriter{
+		enc: encoder,
+		w:   sw,
+		metadata: SzstdMetadata{
+			BlockSize: szstdChunkSize,
+			Size:      0,
+		},
+	}, nil
+}
+
+// Write writes data to the szstd writer in chunks of szstdChunkSize.
+// It handles the block size and metadata updates automatically.
+func (w *SzstdWriter) Write(p []byte) (int, error) {
+	if len(p) == 0 {
+		return 0, nil
+	}
+
+	if w.metadata.BlockData == nil {
+		numBlocks := (len(p) + w.metadata.BlockSize - 1) / w.metadata.BlockSize
+		w.metadata.BlockData = make([]uint32, 1, numBlocks+1)
+		w.metadata.BlockData[0] = 0
+	}
+
+	start := 0
+	total := len(p)
+
+	var writerFunc szstd.FrameSource = func() ([]byte, error) {
+		if start >= total {
+			return nil, nil
+		}
+
+		end := min(start+w.metadata.BlockSize, total)
+		chunk := p[start:end]
+		size := end - start
+
+		w.mu.Lock()
+		w.metadata.Size += int64(size)
+		w.mu.Unlock()
+
+		start = end
+		return chunk, nil
+	}
+
+	// write sizes of compressed blocks in the callback
+	err := w.w.WriteMany(context.Background(), writerFunc,
+		szstd.WithWriteCallback(func(size uint32) {
+			w.mu.Lock()
+			lastOffset := w.metadata.BlockData[len(w.metadata.BlockData)-1]
+			w.metadata.BlockData = append(w.metadata.BlockData, lastOffset+size)
+			w.mu.Unlock()
+		}),
+	)
+	if err != nil {
+		return 0, err
+	}
+
+	return total, nil
+}
+
+// Close closes the SzstdWriter and its underlying encoder.
+func (w *SzstdWriter) Close() error {
+	if err := w.w.Close(); err != nil {
+		return err
+	}
+	if err := w.enc.Close(); err != nil {
+		return err
+	}
+
+	return nil
+}
+
+// GetMetadata returns the metadata of the szstd writer.
+func (w *SzstdWriter) GetMetadata() SzstdMetadata {
+	return w.metadata
+}
+
+// SzstdReaderAt is a reader that allows random access in szstd compressed data.
+type SzstdReaderAt struct {
+	r        szstd.Reader
+	decoder  *zstd.Decoder
+	metadata *SzstdMetadata
+	pos      int64
+	mu       sync.Mutex
+}
+
+// NewReaderAtSzstd creates a new SzstdReaderAt at the specified io.ReadSeeker.
+func NewReaderAtSzstd(rs io.ReadSeeker, meta *SzstdMetadata, offset int64, opts ...zstd.DOption) (*SzstdReaderAt, error) {
+	decoder, err := zstd.NewReader(nil, opts...)
+	if err != nil {
+		return nil, err
+	}
+
+	r, err := szstd.NewReader(rs, decoder)
+	if err != nil {
+		decoder.Close()
+		return nil, err
+	}
+
+	sr := &SzstdReaderAt{
+		r:        r,
+		decoder:  decoder,
+		metadata: meta,
+		pos:      0,
+	}
+
+	// Set initial position to the provided offset
+	if _, err := sr.Seek(offset, io.SeekStart); err != nil {
+		if err := sr.Close(); err != nil {
+			return nil, err
+		}
+		return nil, err
+	}
+
+	return sr, nil
+}
+
+// Seek sets the offset for the next Read.
+func (s *SzstdReaderAt) Seek(offset int64, whence int) (int64, error) {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+
+	pos, err := s.r.Seek(offset, whence)
+	if err == nil {
+		s.pos = pos
+	}
+	return pos, err
+}
+
+func (s *SzstdReaderAt) Read(p []byte) (int, error) {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+
+	n, err := s.r.Read(p)
+	if err == nil {
+		s.pos += int64(n)
+	}
+	return n, err
+}
+
+// ReadAt reads data at the specified offset.
+func (s *SzstdReaderAt) ReadAt(p []byte, off int64) (int, error) {
+	if off < 0 {
+		return 0, errors.New("invalid offset")
+	}
+	if off >= s.metadata.Size {
+		return 0, io.EOF
+	}
+
+	endOff := min(off+int64(len(p)), s.metadata.Size)
+
+	// Find all blocks covered by the range
+	type blockInfo struct {
+		index         int   // Block index
+		offsetInBlock int64 // Offset within the block for starting reading
+		bytesToRead   int64 // How many bytes to read from this block
+	}
+
+	var blocks []blockInfo
+	uncompressedOffset := int64(0)
+	currentOff := off
+
+	for i := 0; i < len(s.metadata.BlockData)-1; i++ {
+		blockUncompressedEnd := min(uncompressedOffset+int64(s.metadata.BlockSize), s.metadata.Size)
+
+		if currentOff < blockUncompressedEnd && endOff > uncompressedOffset {
+			offsetInBlock := max(0, currentOff-uncompressedOffset)
+			bytesToRead := min(blockUncompressedEnd-uncompressedOffset-offsetInBlock, endOff-currentOff)
+
+			blocks = append(blocks, blockInfo{
+				index:         i,
+				offsetInBlock: offsetInBlock,
+				bytesToRead:   bytesToRead,
+			})
+
+			currentOff += bytesToRead
+			if currentOff >= endOff {
+				break
+			}
+		}
+		uncompressedOffset = blockUncompressedEnd
+	}
+
+	if len(blocks) == 0 {
+		return 0, io.EOF
+	}
+
+	// Parallel block decoding
+	type decodeResult struct {
+		index int
+		data  []byte
+		err   error
+	}
+
+	resultCh := make(chan decodeResult, len(blocks))
+	var wg sync.WaitGroup
+	sem := make(chan struct{}, runtime.NumCPU())
+
+	for _, block := range blocks {
+		wg.Add(1)
+		go func(block blockInfo) {
+			defer wg.Done()
+			sem <- struct{}{}
+			defer func() { <-sem }()
+
+			startOffset := int64(s.metadata.BlockData[block.index])
+			endOffset := int64(s.metadata.BlockData[block.index+1])
+			compressedSize := endOffset - startOffset
+
+			compressed := make([]byte, compressedSize)
+			_, err := s.r.ReadAt(compressed, startOffset)
+			if err != nil && err != io.EOF {
+				resultCh <- decodeResult{index: block.index, err: err}
+				return
+			}
+
+			decoded, err := s.decoder.DecodeAll(compressed, nil)
+			if err != nil {
+				resultCh <- decodeResult{index: block.index, err: err}
+				return
+			}
+
+			resultCh <- decodeResult{index: block.index, data: decoded, err: nil}
+		}(block)
+	}
+
+	go func() {
+		wg.Wait()
+		close(resultCh)
+	}()
+
+	// Collect results in block index order
+	totalRead := 0
+	results := make(map[int]decodeResult)
+	expected := len(blocks)
+	minIndex := blocks[0].index
+
+	for res := range resultCh {
+		results[res.index] = res
+		for {
+			if result, ok := results[minIndex]; ok {
+				if result.err != nil {
+					return 0, result.err
+				}
+				// find the corresponding blockInfo
+				var blk blockInfo
+				for _, b := range blocks {
+					if b.index == result.index {
+						blk = b
+						break
+					}
+				}
+
+				start := blk.offsetInBlock
+				end := start + blk.bytesToRead
+				copy(p[totalRead:totalRead+int(blk.bytesToRead)], result.data[start:end])
+				totalRead += int(blk.bytesToRead)
+				minIndex++
+				if minIndex-blocks[0].index >= len(blocks) {
+					break
+				}
+			} else {
+				break
+			}
+		}
+		if len(results) == expected && minIndex-blocks[0].index >= len(blocks) {
+			break
+		}
+	}
+
+	return totalRead, nil
+}
+
+// Close closes the SzstdReaderAt and underlying decoder.
+func (s *SzstdReaderAt) Close() error {
+	if err := s.r.Close(); err != nil {
+		return err
+	}
+	s.decoder.Close()
+	return nil
+}
diff --git a/backend/compress/uncompressed_handler.go b/backend/compress/uncompressed_handler.go
new file mode 100644
index 000000000..c1fc0c794
--- /dev/null
+++ b/backend/compress/uncompressed_handler.go
@@ -0,0 +1,65 @@
+package compress
+
+import (
+	"context"
+	"fmt"
+	"io"
+
+	"github.com/rclone/rclone/fs"
+	"github.com/rclone/rclone/fs/chunkedreader"
+)
+
+// uncompressedModeHandler implements compressionModeHandler for uncompressed files
+type uncompressedModeHandler struct{}
+
+// isCompressible checks the compression ratio of the provided data and returns true if the ratio exceeds
+// the configured threshold
+func (u *uncompressedModeHandler) isCompressible(r io.Reader, compressionMode int) (bool, error) {
+	return false, nil
+}
+
+// newObjectGetOriginalSize returns the original file size from the metadata
+func (u *uncompressedModeHandler) newObjectGetOriginalSize(meta *ObjectMetadata) (int64, error) {
+	return 0, nil
+}
+
+// openGetReadCloser opens a compressed object and returns a ReadCloser in the Open method
+func (u *uncompressedModeHandler) openGetReadCloser(
+	ctx context.Context,
+	o *Object,
+	offset int64,
+	limit int64,
+	cr chunkedreader.ChunkedReader,
+	closer io.Closer,
+	options ...fs.OpenOption,
+) (rc io.ReadCloser, err error) {
+	return o.Object.Open(ctx, options...)
+}
+
+// processFileNameGetFileExtension returns the file extension for the given compression mode
+func (u *uncompressedModeHandler) processFileNameGetFileExtension(compressionMode int) string {
+	return ""
+}
+
+// putCompress compresses the input data and uploads it to the remote, returning the new object and its metadata
+func (u *uncompressedModeHandler) putCompress(
+	ctx context.Context,
+	f *Fs,
+	in io.Reader,
+	src fs.ObjectInfo,
+	options []fs.OpenOption,
+	mimeType string,
+) (fs.Object, *ObjectMetadata, error) {
+	return nil, nil, fmt.Errorf("unsupported compression mode %d", f.mode)
+}
+
+// putUncompressGetNewMetadata returns metadata in the putUncompress method for a specific compression algorithm
+func (u *uncompressedModeHandler) putUncompressGetNewMetadata(o fs.Object, mode int, md5 string, mimeType string, sum []byte) (fs.Object, *ObjectMetadata, error) {
+	return nil, nil, fmt.Errorf("unsupported compression mode %d", Uncompressed)
+}
+
+// This function generates a metadata object for sgzip.GzipMetadata or SzstdMetadata.
+// Warning: This function panics if cmeta is not of the expected type.
+func (u *uncompressedModeHandler) newMetadata(size int64, mode int, cmeta any, md5 string, mimeType string) *ObjectMetadata {
+	return nil
+}
diff --git a/backend/compress/unknown_handler.go b/backend/compress/unknown_handler.go
new file mode 100644
index 000000000..f8d9df589
--- /dev/null
+++ b/backend/compress/unknown_handler.go
@@ -0,0 +1,65 @@
+package compress
+
+import (
+	"context"
+	"fmt"
+	"io"
+
+	"github.com/rclone/rclone/fs"
+	"github.com/rclone/rclone/fs/chunkedreader"
+)
+
+// unknownModeHandler implements compressionModeHandler for unknown compression types
+type unknownModeHandler struct{}
+
+// isCompressible checks the compression ratio of the provided data and returns true if the ratio exceeds
+// the configured threshold
+func (unk *unknownModeHandler) isCompressible(r io.Reader, compressionMode int) (bool, error) {
+	return false, fmt.Errorf("unknown compression mode %d", compressionMode)
+}
+
+// newObjectGetOriginalSize returns the original file size from the metadata
+func (unk *unknownModeHandler) newObjectGetOriginalSize(meta *ObjectMetadata) (int64, error) {
+	return 0, nil
+}
+
+// openGetReadCloser opens a compressed object and returns a ReadCloser in the Open method
+func (unk *unknownModeHandler) openGetReadCloser(
+	ctx context.Context,
+	o *Object,
+	offset int64,
+	limit int64,
+	cr chunkedreader.ChunkedReader,
+	closer io.Closer,
+	options ...fs.OpenOption,
+) (rc io.ReadCloser, err error) {
+	return nil, fmt.Errorf("unknown compression mode %d", o.meta.Mode)
+}
+
+// processFileNameGetFileExtension returns the file extension for the given compression mode
+func (unk *unknownModeHandler) processFileNameGetFileExtension(compressionMode int) string {
+	return ""
+}
+
+// putCompress compresses the input data and uploads it to the remote, returning the new object and its metadata
+func (unk *unknownModeHandler) putCompress(
+	ctx context.Context,
+	f *Fs,
+	in io.Reader,
+	src fs.ObjectInfo,
+	options []fs.OpenOption,
+	mimeType string,
+) (fs.Object, *ObjectMetadata, error) {
+	return nil, nil, fmt.Errorf("unknown compression mode %d", f.mode)
+}
+
+// putUncompressGetNewMetadata returns metadata in the putUncompress method for a specific compression algorithm
+func (unk *unknownModeHandler) putUncompressGetNewMetadata(o fs.Object, mode int, md5 string, mimeType string, sum []byte) (fs.Object, *ObjectMetadata, error) {
+	return nil, nil, fmt.Errorf("unknown compression mode")
+}
+
+// This function generates a metadata object for sgzip.GzipMetadata or SzstdMetadata.
+// Warning: This function panics if cmeta is not of the expected type.
+func (unk *unknownModeHandler) newMetadata(size int64, mode int, cmeta any, md5 string, mimeType string) *ObjectMetadata {
+	return nil
+}
diff --git a/backend/compress/zstd_handler.go b/backend/compress/zstd_handler.go
new file mode 100644
index 000000000..43914427b
--- /dev/null
+++ b/backend/compress/zstd_handler.go
@@ -0,0 +1,192 @@
+package compress
+
+import (
+	"bufio"
+	"bytes"
+	"context"
+	"crypto/md5"
+	"encoding/hex"
+	"errors"
+	"io"
+
+	"github.com/klauspost/compress/zstd"
+
+	"github.com/rclone/rclone/fs"
+	"github.com/rclone/rclone/fs/accounting"
+	"github.com/rclone/rclone/fs/chunkedreader"
+	"github.com/rclone/rclone/fs/hash"
+)
+
+// zstdModeHandler implements compressionModeHandler for zstd
+type zstdModeHandler struct{}
+
+// isCompressible checks the compression ratio of the provided data and returns true if the ratio exceeds
+// the configured threshold
+func (z *zstdModeHandler) isCompressible(r io.Reader, compressionMode int) (bool, error) {
+	var b bytes.Buffer
+	var n int64
+	w, err := NewWriterSzstd(&b, zstd.WithEncoderLevel(zstd.SpeedDefault))
+	if err != nil {
+		return false, err
+	}
+	n, err = io.Copy(w, r)
+	if err != nil {
+		return false, err
+	}
+	err = w.Close()
+	if err != nil {
+		return false, err
+	}
+	ratio := float64(n) / float64(b.Len())
+	return ratio > minCompressionRatio, nil
+}
+
+// newObjectGetOriginalSize returns the original file size from the metadata
+func (z *zstdModeHandler) newObjectGetOriginalSize(meta *ObjectMetadata) (int64, error) {
+	if meta.CompressionMetadataZstd == nil {
+		return 0, errors.New("missing zstd metadata")
+	}
+	return meta.CompressionMetadataZstd.Size, nil
+}
+
+// openGetReadCloser opens a compressed object and returns a ReadCloser in the Open method
+func (z *zstdModeHandler) openGetReadCloser(
+	ctx context.Context,
+	o *Object,
+	offset int64,
+	limit int64,
+	cr chunkedreader.ChunkedReader,
+	closer io.Closer,
+	options ...fs.OpenOption,
+) (rc io.ReadCloser, err error) {
+	var file io.Reader
+
+	if offset != 0 {
+		file, err = NewReaderAtSzstd(cr, o.meta.CompressionMetadataZstd, offset)
+	} else {
+		file, err = zstd.NewReader(cr)
+	}
+	if err != nil {
+		return nil, err
+	}
+
+	var fileReader io.Reader
+	if limit != -1 {
+		fileReader = io.LimitReader(file, limit)
+	} else {
+		fileReader = file
+	}
+	// Return a ReadCloser
+	return ReadCloserWrapper{Reader: fileReader, Closer: closer}, nil
+}
+
+// processFileNameGetFileExtension returns the file extension for the given compression mode
+func (z *zstdModeHandler) processFileNameGetFileExtension(compressionMode int) string {
+	if compressionMode == Zstd {
+		return zstdFileExt
+	}
+
+	return ""
+}
+
+// putCompress compresses the input data and uploads it to the remote, returning the new object and its metadata
+func (z *zstdModeHandler) putCompress(
+	ctx context.Context,
+	f *Fs,
+	in io.Reader,
+	src fs.ObjectInfo,
+	options []fs.OpenOption,
+	mimeType string,
+) (fs.Object, *ObjectMetadata, error) {
+	// Unwrap reader accounting
+	in, wrap := accounting.UnWrap(in)
+
+	// Add the metadata hasher
+	metaHasher := md5.New()
+	in = io.TeeReader(in, metaHasher)
+
+	// Compress the file
+	pipeReader, pipeWriter := io.Pipe()
+
+	resultsZstd := make(chan compressionResult[SzstdMetadata])
+	go func() {
+		writer, err := NewWriterSzstd(pipeWriter, zstd.WithEncoderLevel(zstd.EncoderLevel(f.opt.CompressionLevel)))
+		if err != nil {
+			resultsZstd <- compressionResult[SzstdMetadata]{err: err}
+			close(resultsZstd)
+			return
+		}
+		_, err = io.Copy(writer, in)
+		if wErr := writer.Close(); wErr != nil && err == nil {
+			err = wErr
+		}
+		if cErr := pipeWriter.Close(); cErr != nil && err == nil {
+			err = cErr
+		}
+
+		resultsZstd <- compressionResult[SzstdMetadata]{err: err, meta: writer.GetMetadata()}
+		close(resultsZstd)
+	}()
+
+	wrappedIn := wrap(bufio.NewReaderSize(pipeReader, bufferSize))
+
+	ht := f.Fs.Hashes().GetOne()
+	var hasher *hash.MultiHasher
+	var err error
+	if ht != hash.None {
+		wrappedIn, wrap = accounting.UnWrap(wrappedIn)
+		hasher, err = hash.NewMultiHasherTypes(hash.NewHashSet(ht))
+		if err != nil {
+			return nil, nil, err
+		}
+		wrappedIn = io.TeeReader(wrappedIn, hasher)
+		wrappedIn = wrap(wrappedIn)
+	}
+
+	o, err := f.rcat(ctx, makeDataName(src.Remote(), src.Size(), f.mode), io.NopCloser(wrappedIn), src.ModTime(ctx), options)
+	if err != nil {
+		return nil, nil, err
+	}
+
+	result := <-resultsZstd
+	if result.err != nil {
+		if o != nil {
+			_ = o.Remove(ctx)
+		}
+		return nil, nil, result.err
+	}
+
+	// Build metadata using uncompressed size for filename
+	meta := z.newMetadata(result.meta.Size, f.mode, result.meta, hex.EncodeToString(metaHasher.Sum(nil)), mimeType)
+	if ht != hash.None && hasher != nil {
+		err = f.verifyObjectHash(ctx, o, hasher, ht)
+		if err != nil {
+			return nil, nil, err
+		}
+	}
+	return o, meta, nil
+}
+
+// putUncompressGetNewMetadata returns metadata in the putUncompress method for a specific compression algorithm
+func (z *zstdModeHandler) putUncompressGetNewMetadata(o fs.Object, mode int, md5 string, mimeType string, sum []byte) (fs.Object, *ObjectMetadata, error) {
+	return o, z.newMetadata(o.Size(), mode, SzstdMetadata{}, hex.EncodeToString(sum), mimeType), nil
+}
+
+// This function generates a metadata object for sgzip.GzipMetadata or SzstdMetadata.
+// Warning: This function panics if cmeta is not of the expected type.
+func (z *zstdModeHandler) newMetadata(size int64, mode int, cmeta any, md5 string, mimeType string) *ObjectMetadata {
+	meta, ok := cmeta.(SzstdMetadata)
+	if !ok {
+		panic("invalid cmeta type: expected SzstdMetadata")
+	}
+
+	objMeta := new(ObjectMetadata)
+	objMeta.Size = size
+	objMeta.Mode = mode
+	objMeta.CompressionMetadataGzip = nil
+	objMeta.CompressionMetadataZstd = &meta
+	objMeta.MD5 = md5
+	objMeta.MimeType = mimeType
+
+	return objMeta
+}
diff --git a/docs/content/compress.md b/docs/content/compress.md
index 9fe8d518a..e4c090eec 100644
--- a/docs/content/compress.md
+++ b/docs/content/compress.md
@@ -23,6 +23,7 @@ To use this remote, all you need to do is specify another remote and a
 compression mode to use:
 
 ```text
+$ rclone config
 Current remotes:
 
 Name                 Type
@@ -30,7 +31,6 @@ Name                 Type
 remote_to_press      sometype
 
 e) Edit existing remote
-$ rclone config
 n) New remote
 d) Delete remote
 r) Rename remote
@@ -39,45 +39,74 @@ s) Set configuration password
 q) Quit config
 e/n/d/r/c/s/q> n
 name> compress
+
+Option Storage.
+Type of storage to configure.
+Choose a number from below, or type in your own value.
 ...
- 8 / Compress a remote
-   \ "compress"
+12 / Compress a remote
+   \ (compress)
 ...
 Storage> compress
-** See help for compress backend at: https://rclone.org/compress/ **
 
+Option remote.
 Remote to compress.
-Enter a string value. Press Enter for the default ("").
+Enter a value.
 remote> remote_to_press:subdir 
+
+Option mode.
 Compression mode.
-Enter a string value. Press Enter for the default ("gzip").
-Choose a number from below, or type in your own value
- 1 / Gzip compression balanced for speed and compression strength.
-   \ "gzip"
-compression_mode> gzip
-Edit advanced config? (y/n)
+Choose a number from below, or type in your own value of type string.
+Press Enter for the default (gzip).
+ 1 / Standard gzip compression with fastest parameters.
+   \ (gzip)
+ 2 / Zstandard compression — fast modern algorithm offering adjustable speed-to-compression tradeoffs.
+   \ (zstd)
+mode> gzip
+
+Option level.
+GZIP (levels -2 to 9):
+- -2 — Huffman encoding only. Only use if you know what you're doing.
+- -1 (default) — recommended; equivalent to level 5.
+- 0 — turns off compression.
+- 1–9 — increase compression at the cost of speed. Going past 6 generally offers very little return.
+ 
+ZSTD (levels 0 to 4):
+- 0 — turns off compression entirely.
+- 1 — fastest compression with the lowest ratio.
+- 2 (default) — good balance of speed and compression.
+- 3 — better compression, but uses about 2–3x more CPU than the default.
+- 4 — best possible compression ratio (highest CPU cost).
+ 
+Notes:
+- Choose GZIP for wide compatibility; ZSTD for better speed/ratio tradeoffs.
+- Negative gzip levels: -2 = Huffman-only, -1 = default (≈ level 5).
+Enter a value.
+level> -1
+
+Edit advanced config?
 y) Yes
 n) No (default)
 y/n> n
-Remote config
---------------------
-[compress]
-type = compress
-remote = remote_to_press:subdir
-compression_mode = gzip
---------------------
+
+Configuration complete.
+Options:
+- type: compress
+- remote: remote_to_press:subdir
+- mode: gzip
+- level: -1
+Keep this "compress" remote?
 y) Yes this is OK (default)
 e) Edit this remote
 d) Delete this remote
 y/e/d> y
 ```
 
-### Compression Modes
+### Compression Algorithms
 
-Currently only gzip compression is supported. It provides a decent balance
-between speed and size and is well supported by other applications. Compression
-strength can further be configured via an advanced setting where 0 is no
-compression and 9 is strongest compression.
+- **GZIP** – a well-established and widely adopted algorithm that strikes a solid balance between compression speed and ratio. It supports compression levels from -2 to 9, with the default -1 (roughly equivalent to level 5) offering an effective middle ground for most scenarios.
+
+- **Zstandard (zstd)** – a modern, high-performance algorithm that offers precise control over the trade-off between speed and compression efficiency. Compression levels range from 0 (no compression) to 4 (maximum compression).
 
 ### File types
 
@@ -124,29 +153,38 @@ Properties:
 - Examples:
     - "gzip"
         - Standard gzip compression with fastest parameters.
-
-### Advanced options
-
-Here are the Advanced options specific to compress (Compress a remote).
+    - "zstd"
+        - Zstandard compression — fast modern algorithm offering adjustable speed-to-compression tradeoffs.
 
 #### --compress-level
 
-GZIP compression level (-2 to 9).
-
-Generally -1 (default, equivalent to 5) is recommended.
-Levels 1 to 9 increase compression at the cost of speed. Going past 6 
-generally offers very little return.
-
-Level -2 uses Huffman encoding only. Only use if you know what you
-are doing.
-Level 0 turns off compression.
+GZIP (levels -2 to 9):
+- -2 — Huffman encoding only. Only use if you know what you're doing.
+- -1 (default) — recommended; equivalent to level 5.
+- 0 — turns off compression.
+- 1–9 — increase compression at the cost of speed. Going past 6 generally offers very little return.
+ 
+ZSTD (levels 0 to 4):
+- 0 — turns off compression entirely.
+- 1 — fastest compression with the lowest ratio.
+- 2 (default) — good balance of speed and compression.
+- 3 — better compression, but uses about 2–3x more CPU than the default.
+- 4 — best possible compression ratio (highest CPU cost).
+ 
+Notes:
+- Choose GZIP for wide compatibility; ZSTD for better speed/ratio tradeoffs.
+- Negative gzip levels: -2 = Huffman-only, -1 = default (≈ level 5).
 
 Properties:
 
 - Config:      level
 - Env Var:     RCLONE_COMPRESS_LEVEL
-- Type:        int
-- Default:     -1
+- Type:        string
+- Required:    true
+
+### Advanced options
+
+Here are the Advanced options specific to compress (Compress a remote).
 
 #### --compress-ram-cache-limit
 
diff --git a/fstest/test_all/config.yaml b/fstest/test_all/config.yaml
index eba583e38..a3bc56081 100644
--- a/fstest/test_all/config.yaml
+++ b/fstest/test_all/config.yaml
@@ -133,6 +133,9 @@ backends:
  - backend:  "compress"
    remote:   "TestCompress:"
    fastlist: false
+ - backend:  "compress"
+   remote:   "TestCompressZstd:"
+   fastlist: false
  # - backend:  "compress"
  #   remote:   "TestCompressSwift:"
  #   fastlist: false
diff --git a/go.mod b/go.mod
index d29278d89..9a526e04e 100644
--- a/go.mod
+++ b/go.mod
@@ -1,6 +1,6 @@
 module github.com/rclone/rclone
 
-go 1.24.0
+go 1.24.4
 
 require (
 	bazil.org/fuse v0.0.0-20230120002735-62a210ff1fd5
@@ -11,6 +11,7 @@ require (
 	github.com/Azure/go-ntlmssp v0.0.0-20221128193559-754e69321358
 	github.com/Files-com/files-sdk-go/v3 v3.2.242
 	github.com/Max-Sum/base32768 v0.0.0-20230304063302-18e6ce5945fd
+	github.com/a1ex3/zstd-seekable-format-go/pkg v0.10.0
 	github.com/a8m/tree v0.0.0-20240104212747-2c8764a5f17e
 	github.com/aalpar/deheap v0.0.0-20210914013432-0cc84d79dec3
 	github.com/abbot/go-http-auth v0.4.0
@@ -173,6 +174,7 @@ require (
 	github.com/gofrs/flock v0.12.1 // indirect
 	github.com/gogo/protobuf v1.3.2 // indirect
 	github.com/golang-jwt/jwt/v5 v5.3.0 // indirect
+	github.com/google/btree v1.1.3 // indirect
 	github.com/google/s2a-go v0.1.9 // indirect
 	github.com/googleapis/enterprise-certificate-proxy v0.3.6 // indirect
 	github.com/googleapis/gax-go/v2 v2.15.0 // indirect
diff --git a/go.sum b/go.sum
index 88e176a4b..ab9b93c18 100644
--- a/go.sum
+++ b/go.sum
@@ -90,6 +90,8 @@ github.com/PuerkitoBio/goquery v1.10.3 h1:pFYcNSqHxBD06Fpj/KsbStFRsgRATgnf3LeXiU
 github.com/PuerkitoBio/goquery v1.10.3/go.mod h1:tMUX0zDMHXYlAQk6p35XxQMqMweEKB7iK7iLNd4RH4Y=
 github.com/STARRY-S/zip v0.2.3 h1:luE4dMvRPDOWQdeDdUxUoZkzUIpTccdKdhHHsQJ1fm4=
 github.com/STARRY-S/zip v0.2.3/go.mod h1:lqJ9JdeRipyOQJrYSOtpNAiaesFO6zVDsE8GIGFaoSk=
+github.com/a1ex3/zstd-seekable-format-go/pkg v0.10.0 h1:iLDOF0rdGTrol/q8OfPIIs5kLD8XvA2q75o6Uq/tgak=
+github.com/a1ex3/zstd-seekable-format-go/pkg v0.10.0/go.mod h1:DrEWcQJjz7t5iF2duaiyhg4jyoF0kxOD6LtECNGkZ/Q=
 github.com/a8m/tree v0.0.0-20240104212747-2c8764a5f17e h1:KMVieI1/Ub++GYfnhyFPoGE3g5TUiG4srE3TMGr5nM4=
 github.com/a8m/tree v0.0.0-20240104212747-2c8764a5f17e/go.mod h1:j5astEcUkZQX8lK+KKlQ3NRQ50f4EE8ZjyZpCz3mrH4=
 github.com/aalpar/deheap v0.0.0-20210914013432-0cc84d79dec3 h1:hhdWprfSpFbN7lz3W1gM40vOgvSh1WCSMxYD6gGB4Hs=
@@ -344,6 +346,8 @@ github.com/golang/protobuf v1.5.4 h1:i7eJL8qZTpSEXOPTxNKhASYpMn+8e5Q6AdndVa1dWek
 github.com/golang/protobuf v1.5.4/go.mod h1:lnTiLA8Wa4RWRcIUkrtSVa5nRhsEGBg48fD6rSs7xps=
 github.com/google/btree v0.0.0-20180813153112-4030bb1f1f0c/go.mod h1:lNA+9X1NB3Zf8V7Ke586lFgjr2dZNuvo3lPJSGZ5JPQ=
 github.com/google/btree v1.0.0/go.mod h1:lNA+9X1NB3Zf8V7Ke586lFgjr2dZNuvo3lPJSGZ5JPQ=
+github.com/google/btree v1.1.3 h1:CVpQJjYgC4VbzxeGVHfvZrv1ctoYCAI8vbl07Fcxlyg=
+github.com/google/btree v1.1.3/go.mod h1:qOPhT0dTNdNzV6Z/lhRX0YXUafgPLFUh+gZMl761Gm4=
 github.com/google/go-cmp v0.2.0/go.mod h1:oXzfMopK8JAjlY9xF4vHSVASa0yLyX7SntLO5aqRK0M=
 github.com/google/go-cmp v0.3.0/go.mod h1:8QqcDgzrUqlUb/G2PQTWiueGozuR1884gddMywk6iLU=
 github.com/google/go-cmp v0.3.1/go.mod h1:8QqcDgzrUqlUb/G2PQTWiueGozuR1884gddMywk6iLU=