diff --git a/internal/cli/check.go b/internal/cli/check.go
index 1dffa31..d10cd51 100644
--- a/internal/cli/check.go
+++ b/internal/cli/check.go
@@ -8,8 +8,8 @@ import (
 	"github.com/dustin/go-humanize"
 	"github.com/spf13/afero"
 	"github.com/urfave/cli/v2"
-	"sneak.berlin/go/mfer/internal/checker"
 	"sneak.berlin/go/mfer/internal/log"
+	"sneak.berlin/go/mfer/mfer"
 )
 
 // findManifest looks for a manifest file in the given directory.
@@ -63,7 +63,7 @@ func (mfa *CLIApp) checkManifestOperation(ctx *cli.Context) error {
 	log.Infof("checking manifest %s with base %s", manifestPath, basePath)
 
 	// Create checker
-	chk, err := checker.NewChecker(manifestPath, basePath, mfa.Fs)
+	chk, err := mfer.NewChecker(manifestPath, basePath, mfa.Fs)
 	if err != nil {
 		return fmt.Errorf("failed to load manifest: %w", err)
 	}
@@ -71,12 +71,12 @@ func (mfa *CLIApp) checkManifestOperation(ctx *cli.Context) error {
 	log.Infof("manifest contains %d files, %s", chk.FileCount(), humanize.IBytes(uint64(chk.TotalBytes())))
 
 	// Set up results channel
-	results := make(chan checker.Result, 1)
+	results := make(chan mfer.Result, 1)
 
 	// Set up progress channel
-	var progress chan checker.CheckStatus
+	var progress chan mfer.CheckStatus
 	if showProgress {
-		progress = make(chan checker.CheckStatus, 1)
+		progress = make(chan mfer.CheckStatus, 1)
 		go func() {
 			for status := range progress {
 				if status.ETA > 0 {
@@ -103,7 +103,7 @@ func (mfa *CLIApp) checkManifestOperation(ctx *cli.Context) error {
 	done := make(chan struct{})
 	go func() {
 		for result := range results {
-			if result.Status != checker.StatusOK {
+			if result.Status != mfer.StatusOK {
 				failures++
 				log.Infof("%s: %s (%s)", result.Status, result.Path, result.Message)
 			} else {
@@ -124,7 +124,7 @@ func (mfa *CLIApp) checkManifestOperation(ctx *cli.Context) error {
 
 	// Check for extra files if requested
 	if ctx.Bool("no-extra-files") {
-		extraResults := make(chan checker.Result, 1)
+		extraResults := make(chan mfer.Result, 1)
 		extraDone := make(chan struct{})
 		go func() {
 			for result := range extraResults {
diff --git a/internal/checker/checker.go b/mfer/checker.go
similarity index 80%
rename from internal/checker/checker.go
rename to mfer/checker.go
index f822fa2..147638f 100644
--- a/internal/checker/checker.go
+++ b/mfer/checker.go
@@ -1,4 +1,4 @@
-package checker
+package mfer
 
 import (
 	"bytes"
@@ -12,14 +12,13 @@ import (
 
 	"github.com/multiformats/go-multihash"
 	"github.com/spf13/afero"
-	"sneak.berlin/go/mfer/mfer"
 )
 
 // Result represents the outcome of checking a single file.
 type Result struct {
-	Path    mfer.RelFilePath // Relative path from manifest
-	Status  Status           // Verification result status
-	Message string           // Human-readable description of the result
+	Path    RelFilePath // Relative path from manifest
+	Status  Status      // Verification result status
+	Message string      // Human-readable description of the result
 }
 
 // Status represents the verification status of a file.
@@ -55,22 +54,22 @@ func (s Status) String() string {
 
 // CheckStatus contains progress information for the check operation.
 type CheckStatus struct {
-	TotalFiles   mfer.FileCount // Total number of files in manifest
-	CheckedFiles mfer.FileCount // Number of files checked so far
-	TotalBytes   mfer.FileSize  // Total bytes to verify (sum of all file sizes)
-	CheckedBytes mfer.FileSize  // Bytes verified so far
-	BytesPerSec  float64        // Current throughput rate
-	ETA          time.Duration  // Estimated time to completion
-	Failures     mfer.FileCount // Number of verification failures encountered
+	TotalFiles   FileCount     // Total number of files in manifest
+	CheckedFiles FileCount     // Number of files checked so far
+	TotalBytes   FileSize      // Total bytes to verify (sum of all file sizes)
+	CheckedBytes FileSize      // Bytes verified so far
+	BytesPerSec  float64       // Current throughput rate
+	ETA          time.Duration // Estimated time to completion
+	Failures     FileCount     // Number of verification failures encountered
 }
 
 // Checker verifies files against a manifest.
 type Checker struct {
-	basePath mfer.AbsFilePath
-	files    []*mfer.MFFilePath
+	basePath AbsFilePath
+	files    []*MFFilePath
 	fs       afero.Fs
 	// manifestPaths is a set of paths in the manifest for quick lookup
-	manifestPaths map[mfer.RelFilePath]struct{}
+	manifestPaths map[RelFilePath]struct{}
 }
 
 // NewChecker creates a new Checker for the given manifest, base path, and filesystem.
@@ -81,7 +80,7 @@ func NewChecker(manifestPath string, basePath string, fs afero.Fs) (*Checker, er
 		fs = afero.NewOsFs()
 	}
 
-	m, err := mfer.NewManifestFromFile(fs, manifestPath)
+	m, err := NewManifestFromFile(fs, manifestPath)
 	if err != nil {
 		return nil, err
 	}
@@ -92,13 +91,13 @@ func NewChecker(manifestPath string, basePath string, fs afero.Fs) (*Checker, er
 	}
 
 	files := m.Files()
-	manifestPaths := make(map[mfer.RelFilePath]struct{}, len(files))
+	manifestPaths := make(map[RelFilePath]struct{}, len(files))
 	for _, f := range files {
-		manifestPaths[mfer.RelFilePath(f.Path)] = struct{}{}
+		manifestPaths[RelFilePath(f.Path)] = struct{}{}
 	}
 
 	return &Checker{
-		basePath:      mfer.AbsFilePath(abs),
+		basePath:      AbsFilePath(abs),
 		files:         files,
 		fs:            fs,
 		manifestPaths: manifestPaths,
@@ -106,15 +105,15 @@ func NewChecker(manifestPath string, basePath string, fs afero.Fs) (*Checker, er
 }
 
 // FileCount returns the number of files in the manifest.
-func (c *Checker) FileCount() mfer.FileCount {
-	return mfer.FileCount(len(c.files))
+func (c *Checker) FileCount() FileCount {
+	return FileCount(len(c.files))
 }
 
 // TotalBytes returns the total size of all files in the manifest.
-func (c *Checker) TotalBytes() mfer.FileSize {
-	var total mfer.FileSize
+func (c *Checker) TotalBytes() FileSize {
+	var total FileSize
 	for _, f := range c.files {
-		total += mfer.FileSize(f.Size)
+		total += FileSize(f.Size)
 	}
 	return total
 }
@@ -131,12 +130,12 @@ func (c *Checker) Check(ctx context.Context, results chan<- Result, progress cha
 		defer close(progress)
 	}
 
-	totalFiles := mfer.FileCount(len(c.files))
+	totalFiles := FileCount(len(c.files))
 	totalBytes := c.TotalBytes()
 
-	var checkedFiles mfer.FileCount
-	var checkedBytes mfer.FileSize
-	var failures mfer.FileCount
+	var checkedFiles FileCount
+	var checkedBytes FileSize
+	var failures FileCount
 
 	startTime := time.Now()
 
@@ -186,9 +185,9 @@ func (c *Checker) Check(ctx context.Context, results chan<- Result, progress cha
 	return nil
 }
 
-func (c *Checker) checkFile(entry *mfer.MFFilePath, checkedBytes *mfer.FileSize) Result {
+func (c *Checker) checkFile(entry *MFFilePath, checkedBytes *FileSize) Result {
 	absPath := filepath.Join(string(c.basePath), entry.Path)
-	relPath := mfer.RelFilePath(entry.Path)
+	relPath := RelFilePath(entry.Path)
 
 	// Check if file exists
 	info, err := c.fs.Stat(absPath)
@@ -206,7 +205,7 @@ func (c *Checker) checkFile(entry *mfer.MFFilePath, checkedBytes *mfer.FileSize)
 
 	// Check size
 	if info.Size() != entry.Size {
-		*checkedBytes += mfer.FileSize(info.Size())
+		*checkedBytes += FileSize(info.Size())
 		return Result{
 			Path:    relPath,
 			Status:  StatusSizeMismatch,
@@ -226,7 +225,7 @@ func (c *Checker) checkFile(entry *mfer.MFFilePath, checkedBytes *mfer.FileSize)
 	if err != nil {
 		return Result{Path: relPath, Status: StatusError, Message: err.Error()}
 	}
-	*checkedBytes += mfer.FileSize(n)
+	*checkedBytes += FileSize(n)
 
 	// Encode as multihash and compare
 	computed, err := multihash.Encode(h.Sum(nil), multihash.SHA2_256)
@@ -272,7 +271,7 @@ func (c *Checker) FindExtraFiles(ctx context.Context, results chan<- Result) err
 		if err != nil {
 			return err
 		}
-		relPath := mfer.RelFilePath(rel)
+		relPath := RelFilePath(rel)
 
 		// Check if path is in manifest
 		if _, exists := c.manifestPaths[relPath]; !exists {
diff --git a/internal/checker/checker_test.go b/mfer/checker_test.go
similarity index 88%
rename from internal/checker/checker_test.go
rename to mfer/checker_test.go
index cba9cde..2313bb8 100644
--- a/internal/checker/checker_test.go
+++ b/mfer/checker_test.go
@@ -1,4 +1,4 @@
-package checker
+package mfer
 
 import (
 	"bytes"
@@ -9,7 +9,6 @@ import (
 	"github.com/spf13/afero"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
-	"sneak.berlin/go/mfer/mfer"
 )
 
 func TestStatusString(t *testing.T) {
@@ -37,16 +36,16 @@ func TestStatusString(t *testing.T) {
 func createTestManifest(t *testing.T, fs afero.Fs, manifestPath string, files map[string][]byte) {
 	t.Helper()
 
-	builder := mfer.NewBuilder()
+	builder := NewBuilder()
 	for path, content := range files {
 		reader := bytes.NewReader(content)
-		_, err := builder.AddFile(mfer.RelFilePath(path), mfer.FileSize(len(content)), mfer.ModTime(time.Now()), reader, nil)
+		_, err := builder.AddFile(RelFilePath(path), FileSize(len(content)), ModTime(time.Now()), reader, nil)
 		require.NoError(t, err)
 	}
 
 	var buf bytes.Buffer
 	require.NoError(t, builder.Build(&buf))
-	require.NoError(t, afero.WriteFile(fs, manifestPath, buf.Bytes(), 0644))
+	require.NoError(t, afero.WriteFile(fs, manifestPath, buf.Bytes(), 0o644))
 }
 
 // createFilesOnDisk creates the given files on the filesystem.
@@ -55,8 +54,8 @@ func createFilesOnDisk(t *testing.T, fs afero.Fs, basePath string, files map[str
 
 	for path, content := range files {
 		fullPath := basePath + "/" + path
-		require.NoError(t, fs.MkdirAll(basePath, 0755))
-		require.NoError(t, afero.WriteFile(fs, fullPath, content, 0644))
+		require.NoError(t, fs.MkdirAll(basePath, 0o755))
+		require.NoError(t, afero.WriteFile(fs, fullPath, content, 0o644))
 	}
 }
 
@@ -72,7 +71,7 @@ func TestNewChecker(t *testing.T) {
 		chk, err := NewChecker("/manifest.mf", "/", fs)
 		require.NoError(t, err)
 		assert.NotNil(t, chk)
-		assert.Equal(t, mfer.FileCount(2), chk.FileCount())
+		assert.Equal(t, FileCount(2), chk.FileCount())
 	})
 
 	t.Run("missing manifest", func(t *testing.T) {
@@ -83,7 +82,7 @@ func TestNewChecker(t *testing.T) {
 
 	t.Run("invalid manifest", func(t *testing.T) {
 		fs := afero.NewMemMapFs()
-		require.NoError(t, afero.WriteFile(fs, "/bad.mf", []byte("not a manifest"), 0644))
+		require.NoError(t, afero.WriteFile(fs, "/bad.mf", []byte("not a manifest"), 0o644))
 		_, err := NewChecker("/bad.mf", "/", fs)
 		assert.Error(t, err)
 	})
@@ -101,8 +100,8 @@ func TestCheckerFileCountAndTotalBytes(t *testing.T) {
 	chk, err := NewChecker("/manifest.mf", "/", fs)
 	require.NoError(t, err)
 
-	assert.Equal(t, mfer.FileCount(3), chk.FileCount())
-	assert.Equal(t, mfer.FileSize(2+11+1000), chk.TotalBytes())
+	assert.Equal(t, FileCount(3), chk.FileCount())
+	assert.Equal(t, FileSize(2+11+1000), chk.TotalBytes())
 }
 
 func TestCheckAllFilesOK(t *testing.T) {
@@ -158,7 +157,7 @@ func TestCheckMissingFile(t *testing.T) {
 			okCount++
 		case StatusMissing:
 			missingCount++
-			assert.Equal(t, mfer.RelFilePath("missing.txt"), r.Path)
+			assert.Equal(t, RelFilePath("missing.txt"), r.Path)
 		}
 	}
 
@@ -186,7 +185,7 @@ func TestCheckSizeMismatch(t *testing.T) {
 
 	r := <-results
 	assert.Equal(t, StatusSizeMismatch, r.Status)
-	assert.Equal(t, mfer.RelFilePath("file.txt"), r.Path)
+	assert.Equal(t, RelFilePath("file.txt"), r.Path)
 }
 
 func TestCheckHashMismatch(t *testing.T) {
@@ -212,7 +211,7 @@ func TestCheckHashMismatch(t *testing.T) {
 
 	r := <-results
 	assert.Equal(t, StatusHashMismatch, r.Status)
-	assert.Equal(t, mfer.RelFilePath("file.txt"), r.Path)
+	assert.Equal(t, RelFilePath("file.txt"), r.Path)
 }
 
 func TestCheckWithProgress(t *testing.T) {
@@ -246,11 +245,11 @@ func TestCheckWithProgress(t *testing.T) {
 	assert.NotEmpty(t, progressUpdates)
 	// Final progress should show all files checked
 	final := progressUpdates[len(progressUpdates)-1]
-	assert.Equal(t, mfer.FileCount(2), final.TotalFiles)
-	assert.Equal(t, mfer.FileCount(2), final.CheckedFiles)
-	assert.Equal(t, mfer.FileSize(300), final.TotalBytes)
-	assert.Equal(t, mfer.FileSize(300), final.CheckedBytes)
-	assert.Equal(t, mfer.FileCount(0), final.Failures)
+	assert.Equal(t, FileCount(2), final.TotalFiles)
+	assert.Equal(t, FileCount(2), final.CheckedFiles)
+	assert.Equal(t, FileSize(300), final.TotalBytes)
+	assert.Equal(t, FileSize(300), final.CheckedBytes)
+	assert.Equal(t, FileCount(0), final.Failures)
 }
 
 func TestCheckContextCancellation(t *testing.T) {
@@ -301,7 +300,7 @@ func TestFindExtraFiles(t *testing.T) {
 	}
 
 	assert.Len(t, extras, 1)
-	assert.Equal(t, mfer.RelFilePath("file2.txt"), extras[0].Path)
+	assert.Equal(t, RelFilePath("file2.txt"), extras[0].Path)
 	assert.Equal(t, StatusExtra, extras[0].Status)
 	assert.Equal(t, "not in manifest", extras[0].Message)
 }
@@ -363,8 +362,8 @@ func TestCheckSubdirectories(t *testing.T) {
 	// Create files with full directory structure
 	for path, content := range files {
 		fullPath := "/data/" + path
-		require.NoError(t, fs.MkdirAll("/data/dir1/dir2/dir3", 0755))
-		require.NoError(t, afero.WriteFile(fs, fullPath, content, 0644))
+		require.NoError(t, fs.MkdirAll("/data/dir1/dir2/dir3", 0o755))
+		require.NoError(t, afero.WriteFile(fs, fullPath, content, 0o644))
 	}
 
 	chk, err := NewChecker("/manifest.mf", "/data", fs)
@@ -390,8 +389,8 @@ func TestCheckEmptyManifest(t *testing.T) {
 	chk, err := NewChecker("/manifest.mf", "/data", fs)
 	require.NoError(t, err)
 
-	assert.Equal(t, mfer.FileCount(0), chk.FileCount())
-	assert.Equal(t, mfer.FileSize(0), chk.TotalBytes())
+	assert.Equal(t, FileCount(0), chk.FileCount())
+	assert.Equal(t, FileSize(0), chk.TotalBytes())
 
 	results := make(chan Result, 10)
 	err = chk.Check(context.Background(), results, nil)