diff --git a/CHANGELOG.md b/CHANGELOG.md
index 0fe46c9..3f389a2 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -4,6 +4,9 @@ This document outlines major changes between releases.
 
 ## [Unreleased]
 
+### Added
+- Billing metrics (TrueCloudLab#5)
+
 ### Changed
 - Update neo-go to v0.101.0 (#14)
 - Update viper to v1.15.0 (#14)
diff --git a/api/handler/util.go b/api/handler/util.go
index 4516cf8..61af738 100644
--- a/api/handler/util.go
+++ b/api/handler/util.go
@@ -42,6 +42,10 @@ func transformToS3Error(err error) error {
 	return errors.GetAPIError(errors.ErrInternalError)
 }
 
+func (h *handler) ResolveBucket(ctx context.Context, bucket string) (*data.BucketInfo, error) {
+	return h.obj.GetBucketInfo(ctx, bucket)
+}
+
 func (h *handler) getBucketAndCheckOwner(r *http.Request, bucket string, header ...string) (*data.BucketInfo, error) {
 	bktInfo, err := h.obj.GetBucketInfo(r.Context(), bucket)
 	if err != nil {
diff --git a/api/metrics.go b/api/metrics.go
new file mode 100644
index 0000000..eee2fe0
--- /dev/null
+++ b/api/metrics.go
@@ -0,0 +1,473 @@
+package api
+
+import (
+	"context"
+	"io"
+	"net/http"
+	"strings"
+	"sync"
+	"sync/atomic"
+	"time"
+
+	"github.com/TrueCloudLab/frostfs-s3-gw/creds/accessbox"
+	"github.com/TrueCloudLab/frostfs-sdk-go/bearer"
+	"github.com/prometheus/client_golang/prometheus"
+)
+
+type TrafficType int
+
+const (
+	UnknownTraffic TrafficType = iota
+	INTraffic      TrafficType = iota
+	OUTTraffic     TrafficType = iota
+)
+
+func (t TrafficType) String() string {
+	switch t {
+	case 1:
+		return "IN"
+	case 2:
+		return "OUT"
+	default:
+		return "Unknown"
+	}
+}
+
+type RequestType int
+
+const (
+	UNKNOWNRequest RequestType = iota
+	HEADRequest    RequestType = iota
+	PUTRequest     RequestType = iota
+	LISTRequest    RequestType = iota
+	GETRequest     RequestType = iota
+	DELETERequest  RequestType = iota
+)
+
+func (t RequestType) String() string {
+	switch t {
+	case 1:
+		return "HEAD"
+	case 2:
+		return "PUT"
+	case 3:
+		return "LIST"
+	case 4:
+		return "GET"
+	case 5:
+		return "DELETE"
+	default:
+		return "Unknown"
+	}
+}
+
+func RequestTypeFromAPI(api string) RequestType {
+	switch api {
+	case "Options", "HeadObject", "HeadBucket":
+		return HEADRequest
+	case "CreateMultipartUpload", "UploadPartCopy", "UploadPart", "CompleteMultipartUpload",
+		"PutObjectACL", "PutObjectTagging", "CopyObject", "PutObjectRetention", "PutObjectLegalHold",
+		"PutObject", "PutBucketCors", "PutBucketACL", "PutBucketLifecycle", "PutBucketEncryption",
+		"PutBucketPolicy", "PutBucketObjectLockConfig", "PutBucketTagging", "PutBucketVersioning",
+		"PutBucketNotification", "CreateBucket", "PostObject":
+		return PUTRequest
+	case "ListObjectParts", "ListMultipartUploads", "ListObjectsV2M", "ListObjectsV2", "ListBucketVersions",
+		"ListObjectsV1", "ListBuckets":
+		return LISTRequest
+	case "GetObjectACL", "GetObjectTagging", "SelectObjectContent", "GetObjectRetention", "getobjectlegalhold",
+		"GetObjectAttributes", "GetObject", "GetBucketLocation", "GetBucketPolicy",
+		"GetBucketLifecycle", "GetBucketEncryption", "GetBucketCors", "GetBucketACL",
+		"GetBucketWebsite", "GetBucketAccelerate", "GetBucketRequestPayment", "GetBucketLogging",
+		"GetBucketReplication", "GetBucketTagging", "GetBucketObjectLockConfig",
+		"GetBucketVersioning", "GetBucketNotification", "ListenBucketNotification":
+		return GETRequest
+	case "AbortMultipartUpload", "DeleteObjectTagging", "DeleteObject", "DeleteBucketCors",
+		"DeleteBucketWebsite", "DeleteBucketTagging", "DeleteMultipleObjects", "DeleteBucketPolicy",
+		"DeleteBucketLifecycle", "DeleteBucketEncryption", "DeleteBucket":
+		return DELETERequest
+	default:
+		return UNKNOWNRequest
+	}
+}
+
+type OperationList [6]int
+
+type (
+	// HTTPAPIStats holds statistics information about
+	// the API given in the requests.
+	HTTPAPIStats struct {
+		apiStats map[string]int
+		sync.RWMutex
+	}
+
+	UsersAPIStats struct {
+		users map[string]*userAPIStats
+		sync.RWMutex
+	}
+
+	bucketKey struct {
+		name string
+		cid  string
+	}
+
+	bucketStat struct {
+		Operations OperationList
+		InTraffic  uint64
+		OutTraffic uint64
+	}
+
+	userAPIStats struct {
+		buckets map[bucketKey]bucketStat
+		user    string
+	}
+
+	UserBucketInfo struct {
+		User        string
+		Bucket      string
+		ContainerID string
+	}
+
+	UserMetricsInfo struct {
+		UserBucketInfo
+		Operation RequestType
+		Requests  int
+	}
+
+	UserTrafficMetricsInfo struct {
+		UserBucketInfo
+		Type  TrafficType
+		Value uint64
+	}
+
+	UserMetrics struct {
+		Requests []UserMetricsInfo
+		Traffic  []UserTrafficMetricsInfo
+	}
+
+	// HTTPStats holds statistics information about
+	// HTTP requests made by all clients.
+	HTTPStats struct {
+		usersS3Requests   UsersAPIStats
+		currentS3Requests HTTPAPIStats
+		totalS3Requests   HTTPAPIStats
+		totalS3Errors     HTTPAPIStats
+
+		totalInputBytes  uint64
+		totalOutputBytes uint64
+	}
+
+	readCounter struct {
+		io.ReadCloser
+		countBytes uint64
+	}
+
+	writeCounter struct {
+		http.ResponseWriter
+		countBytes uint64
+	}
+
+	responseWrapper struct {
+		sync.Once
+		http.ResponseWriter
+
+		statusCode int
+		startTime  time.Time
+	}
+)
+
+const systemPath = "/system"
+
+var (
+	httpStatsMetric      = new(HTTPStats)
+	httpRequestsDuration = prometheus.NewHistogramVec(
+		prometheus.HistogramOpts{
+			Name:    "frostfs_s3_request_seconds",
+			Help:    "Time taken by requests served by current FrostFS S3 Gate instance",
+			Buckets: []float64{.05, .1, .25, .5, 1, 2.5, 5, 10},
+		},
+		[]string{"api"},
+	)
+)
+
+// Collects HTTP metrics for FrostFS S3 Gate in Prometheus specific format
+// and sends to the given channel.
+func collectHTTPMetrics(ch chan<- prometheus.Metric) {
+	for api, value := range httpStatsMetric.currentS3Requests.Load() {
+		ch <- prometheus.MustNewConstMetric(
+			prometheus.NewDesc(
+				prometheus.BuildFQName("frostfs_s3", "requests", "current"),
+				"Total number of running s3 requests in current FrostFS S3 Gate instance",
+				[]string{"api"}, nil),
+			prometheus.CounterValue,
+			float64(value),
+			api,
+		)
+	}
+
+	for api, value := range httpStatsMetric.totalS3Requests.Load() {
+		ch <- prometheus.MustNewConstMetric(
+			prometheus.NewDesc(
+				prometheus.BuildFQName("frostfs_s3", "requests", "total"),
+				"Total number of s3 requests in current FrostFS S3 Gate instance",
+				[]string{"api"}, nil),
+			prometheus.CounterValue,
+			float64(value),
+			api,
+		)
+	}
+
+	for api, value := range httpStatsMetric.totalS3Errors.Load() {
+		ch <- prometheus.MustNewConstMetric(
+			prometheus.NewDesc(
+				prometheus.BuildFQName("frostfs_s3", "errors", "total"),
+				"Total number of s3 errors in current FrostFS S3 Gate instance",
+				[]string{"api"}, nil),
+			prometheus.CounterValue,
+			float64(value),
+			api,
+		)
+	}
+}
+
+func collectUserMetrics(ch chan<- prometheus.Metric) {
+	userMetrics := httpStatsMetric.usersS3Requests.DumpMetrics()
+
+	for _, value := range userMetrics.Requests {
+		ch <- prometheus.MustNewConstMetric(
+			prometheus.NewDesc(
+				prometheus.BuildFQName("frostfs_s3", "user_requests", "count"),
+				"",
+				[]string{"user", "bucket", "cid", "operation"}, nil),
+			prometheus.CounterValue,
+			float64(value.Requests),
+			value.User,
+			value.Bucket,
+			value.ContainerID,
+			value.Operation.String(),
+		)
+	}
+
+	for _, value := range userMetrics.Traffic {
+		ch <- prometheus.MustNewConstMetric(
+			prometheus.NewDesc(
+				prometheus.BuildFQName("frostfs_s3", "user_traffic", "bytes"),
+				"",
+				[]string{"user", "bucket", "cid", "type"}, nil),
+			prometheus.CounterValue,
+			float64(value.Value),
+			value.User,
+			value.Bucket,
+			value.ContainerID,
+			value.Type.String(),
+		)
+	}
+}
+
+// CIDResolveFunc is a func to resolve CID in Stats handler.
+type CIDResolveFunc func(ctx context.Context, reqInfo *ReqInfo) (cnrID string)
+
+// Stats is a handler that update metrics.
+func Stats(f http.HandlerFunc, resolveCID CIDResolveFunc) http.HandlerFunc {
+	return func(w http.ResponseWriter, r *http.Request) {
+		reqInfo := GetReqInfo(r.Context())
+
+		httpStatsMetric.currentS3Requests.Inc(reqInfo.API)
+		defer httpStatsMetric.currentS3Requests.Dec(reqInfo.API)
+
+		in := &readCounter{ReadCloser: r.Body}
+		out := &writeCounter{ResponseWriter: w}
+
+		r.Body = in
+
+		statsWriter := &responseWrapper{
+			ResponseWriter: out,
+			startTime:      time.Now(),
+		}
+
+		f(statsWriter, r)
+
+		// Time duration in secs since the call started.
+		// We don't need to do nanosecond precision here
+		// simply for the fact that it is not human-readable.
+		durationSecs := time.Since(statsWriter.startTime).Seconds()
+
+		user := resolveUser(r.Context())
+		cnrID := resolveCID(r.Context(), reqInfo)
+		httpStatsMetric.usersS3Requests.Update(user, reqInfo.BucketName, cnrID, RequestTypeFromAPI(reqInfo.API), in.countBytes, out.countBytes)
+
+		code := statsWriter.statusCode
+		// A successful request has a 2xx response code
+		successReq := code >= http.StatusOK && code < http.StatusMultipleChoices
+		if !strings.HasSuffix(r.URL.Path, systemPath) {
+			httpStatsMetric.totalS3Requests.Inc(reqInfo.API)
+			if !successReq && code != 0 {
+				httpStatsMetric.totalS3Errors.Inc(reqInfo.API)
+			}
+		}
+
+		if r.Method == http.MethodGet {
+			// Increment the prometheus http request response histogram with appropriate label
+			httpRequestsDuration.With(prometheus.Labels{"api": reqInfo.API}).Observe(durationSecs)
+		}
+
+		atomic.AddUint64(&httpStatsMetric.totalInputBytes, in.countBytes)
+		atomic.AddUint64(&httpStatsMetric.totalOutputBytes, out.countBytes)
+	}
+}
+
+func resolveUser(ctx context.Context) string {
+	user := "anon"
+	if bd, ok := ctx.Value(BoxData).(*accessbox.Box); ok && bd != nil && bd.Gate != nil && bd.Gate.BearerToken != nil {
+		user = bearer.ResolveIssuer(*bd.Gate.BearerToken).String()
+	}
+	return user
+}
+
+// Inc increments the api stats counter.
+func (stats *HTTPAPIStats) Inc(api string) {
+	if stats == nil {
+		return
+	}
+	stats.Lock()
+	defer stats.Unlock()
+	if stats.apiStats == nil {
+		stats.apiStats = make(map[string]int)
+	}
+	stats.apiStats[api]++
+}
+
+// Dec increments the api stats counter.
+func (stats *HTTPAPIStats) Dec(api string) {
+	if stats == nil {
+		return
+	}
+	stats.Lock()
+	defer stats.Unlock()
+	if val, ok := stats.apiStats[api]; ok && val > 0 {
+		stats.apiStats[api]--
+	}
+}
+
+// Load returns the recorded stats.
+func (stats *HTTPAPIStats) Load() map[string]int {
+	stats.Lock()
+	defer stats.Unlock()
+	var apiStats = make(map[string]int, len(stats.apiStats))
+	for k, v := range stats.apiStats {
+		apiStats[k] = v
+	}
+	return apiStats
+}
+
+func (u *UsersAPIStats) Update(user, bucket, cnrID string, reqType RequestType, in, out uint64) {
+	u.Lock()
+	defer u.Unlock()
+
+	usersStat := u.users[user]
+	if usersStat == nil {
+		if u.users == nil {
+			u.users = make(map[string]*userAPIStats)
+		}
+		usersStat = &userAPIStats{
+			buckets: make(map[bucketKey]bucketStat, 1),
+			user:    user,
+		}
+		u.users[user] = usersStat
+	}
+
+	key := bucketKey{
+		name: bucket,
+		cid:  cnrID,
+	}
+
+	bktStat := usersStat.buckets[key]
+	bktStat.Operations[reqType]++
+	bktStat.InTraffic += in
+	bktStat.OutTraffic += out
+	usersStat.buckets[key] = bktStat
+}
+
+func (u *UsersAPIStats) DumpMetrics() UserMetrics {
+	u.Lock()
+	defer u.Unlock()
+
+	result := UserMetrics{
+		Requests: make([]UserMetricsInfo, 0, len(u.users)),
+		Traffic:  make([]UserTrafficMetricsInfo, 0, len(u.users)),
+	}
+
+	for user, userStat := range u.users {
+		for key, bktStat := range userStat.buckets {
+			userBktInfo := UserBucketInfo{
+				User:        user,
+				Bucket:      key.name,
+				ContainerID: key.cid,
+			}
+
+			if bktStat.InTraffic != 0 {
+				result.Traffic = append(result.Traffic, UserTrafficMetricsInfo{
+					UserBucketInfo: userBktInfo,
+					Type:           INTraffic,
+					Value:          bktStat.InTraffic,
+				})
+			}
+
+			if bktStat.OutTraffic != 0 {
+				result.Traffic = append(result.Traffic, UserTrafficMetricsInfo{
+					UserBucketInfo: userBktInfo,
+					Type:           OUTTraffic,
+					Value:          bktStat.OutTraffic,
+				})
+			}
+
+			for op, val := range bktStat.Operations {
+				if val != 0 {
+					result.Requests = append(result.Requests, UserMetricsInfo{
+						UserBucketInfo: userBktInfo,
+						Operation:      RequestType(op),
+						Requests:       val,
+					})
+				}
+			}
+		}
+	}
+
+	u.users = make(map[string]*userAPIStats)
+
+	return result
+}
+
+func (st *HTTPStats) getInputBytes() uint64 {
+	return atomic.LoadUint64(&st.totalInputBytes)
+}
+
+func (st *HTTPStats) getOutputBytes() uint64 {
+	return atomic.LoadUint64(&st.totalOutputBytes)
+}
+
+// WriteHeader -- writes http status code.
+func (w *responseWrapper) WriteHeader(code int) {
+	w.Do(func() {
+		w.statusCode = code
+		w.ResponseWriter.WriteHeader(code)
+	})
+}
+
+// Flush -- calls the underlying Flush.
+func (w *responseWrapper) Flush() {
+	if f, ok := w.ResponseWriter.(http.Flusher); ok {
+		f.Flush()
+	}
+}
+
+func (w *writeCounter) Write(p []byte) (int, error) {
+	n, err := w.ResponseWriter.Write(p)
+	atomic.AddUint64(&w.countBytes, uint64(n))
+	return n, err
+}
+
+func (r *readCounter) Read(p []byte) (int, error) {
+	n, err := r.ReadCloser.Read(p)
+	atomic.AddUint64(&r.countBytes, uint64(n))
+	return n, err
+}
diff --git a/api/metrics/api.go b/api/metrics/api.go
deleted file mode 100644
index 92a5801..0000000
--- a/api/metrics/api.go
+++ /dev/null
@@ -1,229 +0,0 @@
-package metrics
-
-import (
-	"io"
-	"net/http"
-	"strings"
-	"sync"
-	"sync/atomic"
-	"time"
-
-	"github.com/prometheus/client_golang/prometheus"
-)
-
-type (
-	// HTTPAPIStats holds statistics information about
-	// the API given in the requests.
-	HTTPAPIStats struct {
-		apiStats map[string]int
-		sync.RWMutex
-	}
-
-	// HTTPStats holds statistics information about
-	// HTTP requests made by all clients.
-	HTTPStats struct {
-		currentS3Requests HTTPAPIStats
-		totalS3Requests   HTTPAPIStats
-		totalS3Errors     HTTPAPIStats
-
-		totalInputBytes  uint64
-		totalOutputBytes uint64
-	}
-
-	readCounter struct {
-		io.ReadCloser
-		countBytes uint64
-	}
-
-	writeCounter struct {
-		http.ResponseWriter
-		countBytes uint64
-	}
-
-	responseWrapper struct {
-		sync.Once
-		http.ResponseWriter
-
-		statusCode int
-		startTime  time.Time
-	}
-)
-
-const systemPath = "/system"
-
-var (
-	httpStatsMetric      = new(HTTPStats)
-	httpRequestsDuration = prometheus.NewHistogramVec(
-		prometheus.HistogramOpts{
-			Name:    "frostfs_s3_request_seconds",
-			Help:    "Time taken by requests served by current FrostFS S3 Gate instance",
-			Buckets: []float64{.05, .1, .25, .5, 1, 2.5, 5, 10},
-		},
-		[]string{"api"},
-	)
-)
-
-// Collects HTTP metrics for FrostFS S3 Gate in Prometheus specific format
-// and sends to the given channel.
-func collectHTTPMetrics(ch chan<- prometheus.Metric) {
-	for api, value := range httpStatsMetric.currentS3Requests.Load() {
-		ch <- prometheus.MustNewConstMetric(
-			prometheus.NewDesc(
-				prometheus.BuildFQName("frostfs_s3", "requests", "current"),
-				"Total number of running s3 requests in current FrostFS S3 Gate instance",
-				[]string{"api"}, nil),
-			prometheus.CounterValue,
-			float64(value),
-			api,
-		)
-	}
-
-	for api, value := range httpStatsMetric.totalS3Requests.Load() {
-		ch <- prometheus.MustNewConstMetric(
-			prometheus.NewDesc(
-				prometheus.BuildFQName("frostfs_s3", "requests", "total"),
-				"Total number of s3 requests in current FrostFS S3 Gate instance",
-				[]string{"api"}, nil),
-			prometheus.CounterValue,
-			float64(value),
-			api,
-		)
-	}
-
-	for api, value := range httpStatsMetric.totalS3Errors.Load() {
-		ch <- prometheus.MustNewConstMetric(
-			prometheus.NewDesc(
-				prometheus.BuildFQName("frostfs_s3", "errors", "total"),
-				"Total number of s3 errors in current FrostFS S3 Gate instance",
-				[]string{"api"}, nil),
-			prometheus.CounterValue,
-			float64(value),
-			api,
-		)
-	}
-}
-
-// APIStats wraps http handler for api with basic statistics collection.
-func APIStats(api string, f http.HandlerFunc) http.HandlerFunc {
-	return func(w http.ResponseWriter, r *http.Request) {
-		httpStatsMetric.currentS3Requests.Inc(api)
-		defer httpStatsMetric.currentS3Requests.Dec(api)
-
-		in := &readCounter{ReadCloser: r.Body}
-		out := &writeCounter{ResponseWriter: w}
-
-		r.Body = in
-
-		statsWriter := &responseWrapper{
-			ResponseWriter: out,
-			startTime:      time.Now(),
-		}
-
-		f.ServeHTTP(statsWriter, r)
-
-		// Time duration in secs since the call started.
-		// We don't need to do nanosecond precision here
-		// simply for the fact that it is not human readable.
-		durationSecs := time.Since(statsWriter.startTime).Seconds()
-
-		httpStatsMetric.updateStats(api, statsWriter, r, durationSecs)
-
-		atomic.AddUint64(&httpStatsMetric.totalInputBytes, in.countBytes)
-		atomic.AddUint64(&httpStatsMetric.totalOutputBytes, out.countBytes)
-	}
-}
-
-// Inc increments the api stats counter.
-func (stats *HTTPAPIStats) Inc(api string) {
-	if stats == nil {
-		return
-	}
-	stats.Lock()
-	defer stats.Unlock()
-	if stats.apiStats == nil {
-		stats.apiStats = make(map[string]int)
-	}
-	stats.apiStats[api]++
-}
-
-// Dec increments the api stats counter.
-func (stats *HTTPAPIStats) Dec(api string) {
-	if stats == nil {
-		return
-	}
-	stats.Lock()
-	defer stats.Unlock()
-	if val, ok := stats.apiStats[api]; ok && val > 0 {
-		stats.apiStats[api]--
-	}
-}
-
-// Load returns the recorded stats.
-func (stats *HTTPAPIStats) Load() map[string]int {
-	stats.Lock()
-	defer stats.Unlock()
-	var apiStats = make(map[string]int, len(stats.apiStats))
-	for k, v := range stats.apiStats {
-		apiStats[k] = v
-	}
-	return apiStats
-}
-
-func (st *HTTPStats) getInputBytes() uint64 {
-	return atomic.LoadUint64(&st.totalInputBytes)
-}
-
-func (st *HTTPStats) getOutputBytes() uint64 {
-	return atomic.LoadUint64(&st.totalOutputBytes)
-}
-
-// Update statistics from http request and response data.
-func (st *HTTPStats) updateStats(api string, w http.ResponseWriter, r *http.Request, durationSecs float64) {
-	var code int
-
-	if res, ok := w.(*responseWrapper); ok {
-		code = res.statusCode
-	}
-
-	// A successful request has a 2xx response code
-	successReq := code >= http.StatusOK && code < http.StatusMultipleChoices
-
-	if !strings.HasSuffix(r.URL.Path, systemPath) {
-		st.totalS3Requests.Inc(api)
-		if !successReq && code != 0 {
-			st.totalS3Errors.Inc(api)
-		}
-	}
-
-	if r.Method == http.MethodGet {
-		// Increment the prometheus http request response histogram with appropriate label
-		httpRequestsDuration.With(prometheus.Labels{"api": api}).Observe(durationSecs)
-	}
-}
-
-// WriteHeader -- writes http status code.
-func (w *responseWrapper) WriteHeader(code int) {
-	w.Do(func() {
-		w.statusCode = code
-		w.ResponseWriter.WriteHeader(code)
-	})
-}
-
-// Flush -- calls the underlying Flush.
-func (w *responseWrapper) Flush() {
-	if f, ok := w.ResponseWriter.(http.Flusher); ok {
-		f.Flush()
-	}
-}
-
-func (w *writeCounter) Write(p []byte) (int, error) {
-	n, err := w.ResponseWriter.Write(p)
-	atomic.AddUint64(&w.countBytes, uint64(n))
-	return n, err
-}
-
-func (r *readCounter) Read(p []byte) (int, error) {
-	n, err := r.ReadCloser.Read(p)
-	atomic.AddUint64(&r.countBytes, uint64(n))
-	return n, err
-}
diff --git a/api/metrics/collector.go b/api/metrics_collector.go
similarity index 97%
rename from api/metrics/collector.go
rename to api/metrics_collector.go
index 5972e9a..eac7c5b 100644
--- a/api/metrics/collector.go
+++ b/api/metrics_collector.go
@@ -1,4 +1,4 @@
-package metrics
+package api
 
 import (
 	"github.com/TrueCloudLab/frostfs-s3-gw/internal/version"
@@ -64,5 +64,6 @@ func (s *stats) Collect(ch chan<- prometheus.Metric) {
 
 	// connect collectors
 	collectHTTPMetrics(ch)
+	collectUserMetrics(ch)
 	collectNetworkMetrics(ch)
 }
diff --git a/api/router.go b/api/router.go
index 7e49d67..793755f 100644
--- a/api/router.go
+++ b/api/router.go
@@ -6,7 +6,7 @@ import (
 	"sync"
 
 	"github.com/TrueCloudLab/frostfs-s3-gw/api/auth"
-	"github.com/TrueCloudLab/frostfs-s3-gw/api/metrics"
+	"github.com/TrueCloudLab/frostfs-s3-gw/api/data"
 	"github.com/google/uuid"
 	"github.com/gorilla/mux"
 	"go.uber.org/zap"
@@ -82,6 +82,8 @@ type (
 		AbortMultipartUploadHandler(http.ResponseWriter, *http.Request)
 		ListPartsHandler(w http.ResponseWriter, r *http.Request)
 		ListMultipartUploadsHandler(http.ResponseWriter, *http.Request)
+
+		ResolveBucket(ctx context.Context, bucket string) (*data.BucketInfo, error)
 	}
 
 	// mimeType represents various MIME types used in API responses.
@@ -106,7 +108,7 @@ const (
 	MimeXML mimeType = "application/xml"
 )
 
-var _ = logErrorResponse
+var _ = logSuccessResponse
 
 func (lrw *logResponseWriter) WriteHeader(code int) {
 	lrw.Do(func() {
@@ -145,7 +147,37 @@ func appendCORS(handler Handler) mux.MiddlewareFunc {
 	}
 }
 
-func logErrorResponse(l *zap.Logger) mux.MiddlewareFunc {
+// BucketResolveFunc is a func to resolve bucket info by name.
+type BucketResolveFunc func(ctx context.Context, bucket string) (*data.BucketInfo, error)
+
+// metricsMiddleware wraps http handler for api with basic statistics collection.
+func metricsMiddleware(log *zap.Logger, resolveBucket BucketResolveFunc) mux.MiddlewareFunc {
+	return func(h http.Handler) http.Handler {
+		return Stats(h.ServeHTTP, resolveCID(log, resolveBucket))
+	}
+}
+
+// resolveCID forms CIDResolveFunc using BucketResolveFunc.
+func resolveCID(log *zap.Logger, resolveBucket BucketResolveFunc) CIDResolveFunc {
+	return func(ctx context.Context, reqInfo *ReqInfo) (cnrID string) {
+		if reqInfo.BucketName == "" || reqInfo.API == "CreateBucket" || reqInfo.API == "" {
+			return ""
+		}
+
+		bktInfo, err := resolveBucket(ctx, reqInfo.BucketName)
+		if err != nil {
+			log.Debug("failed to resolve CID",
+				zap.String("request_id", reqInfo.RequestID), zap.String("method", reqInfo.API),
+				zap.String("bucket", reqInfo.BucketName), zap.String("object", reqInfo.ObjectName),
+				zap.Error(err))
+			return ""
+		}
+
+		return bktInfo.CID.EncodeToString()
+	}
+}
+
+func logSuccessResponse(l *zap.Logger) mux.MiddlewareFunc {
 	return func(h http.Handler) http.Handler {
 		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 			lw := &logResponseWriter{ResponseWriter: w}
@@ -183,6 +215,30 @@ func GetRequestID(v interface{}) string {
 	}
 }
 
+func setErrorAPI(apiName string, h http.Handler) http.Handler {
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		ctx := SetReqInfo(r.Context(), &ReqInfo{API: apiName})
+		h.ServeHTTP(w, r.WithContext(ctx))
+	})
+}
+
+// attachErrorHandler set NotFoundHandler and MethodNotAllowedHandler for mux.Router.
+func attachErrorHandler(api *mux.Router, log *zap.Logger, h Handler, center auth.Center) {
+	middlewares := []mux.MiddlewareFunc{
+		AuthMiddleware(log, center),
+		metricsMiddleware(log, h.ResolveBucket),
+	}
+
+	var errorHandler http.Handler = http.HandlerFunc(errorResponseHandler)
+	for i := len(middlewares) - 1; i >= 0; i-- {
+		errorHandler = middlewares[i](errorHandler)
+	}
+
+	// If none of the routes match, add default error handler routes
+	api.NotFoundHandler = setErrorAPI("NotFound", errorHandler)
+	api.MethodNotAllowedHandler = setErrorAPI("MethodNotAllowed", errorHandler)
+}
+
 // Attach adds S3 API handlers from h to r for domains with m client limit using
 // center authentication and log logger.
 func Attach(r *mux.Router, domains []string, m MaxClients, h Handler, center auth.Center, log *zap.Logger) {
@@ -192,12 +248,16 @@ func Attach(r *mux.Router, domains []string, m MaxClients, h Handler, center aut
 		// -- prepare request
 		setRequestID,
 
+		// Attach user authentication for all S3 routes.
+		AuthMiddleware(log, center),
+
+		metricsMiddleware(log, h.ResolveBucket),
+
 		// -- logging error requests
-		logErrorResponse(log),
+		logSuccessResponse(log),
 	)
 
-	// Attach user authentication for all S3 routes.
-	AttachUserAuth(api, center, log)
+	attachErrorHandler(api, log, h, center)
 
 	buckets := make([]*mux.Router, 0, len(domains)+1)
 	buckets = append(buckets, api.PathPrefix("/{bucket}").Subrouter())
@@ -213,277 +273,327 @@ func Attach(r *mux.Router, domains []string, m MaxClients, h Handler, center aut
 			// -- append CORS headers to a response for
 			appendCORS(h),
 		)
-		bucket.Methods(http.MethodOptions).HandlerFunc(m.Handle(metrics.APIStats("preflight", h.Preflight))).Name("Options")
+		bucket.Methods(http.MethodOptions).HandlerFunc(
+			m.Handle(h.Preflight)).
+			Name("Options")
 		bucket.Methods(http.MethodHead).Path("/{object:.+}").HandlerFunc(
-			m.Handle(metrics.APIStats("headobject", h.HeadObjectHandler))).Name("HeadObject")
+			m.Handle(h.HeadObjectHandler)).
+			Name("HeadObject")
 		// CopyObjectPart
-		bucket.Methods(http.MethodPut).Path("/{object:.+}").Headers(hdrAmzCopySource, "").HandlerFunc(m.Handle(metrics.APIStats("uploadpartcopy", h.UploadPartCopy))).Queries("partNumber", "{partNumber:[0-9]+}", "uploadId", "{uploadId:.*}").
+		bucket.Methods(http.MethodPut).Path("/{object:.+}").Headers(hdrAmzCopySource, "").HandlerFunc(
+			m.Handle(h.UploadPartCopy)).
+			Queries("partNumber", "{partNumber:[0-9]+}", "uploadId", "{uploadId:.*}").
 			Name("UploadPartCopy")
 		// PutObjectPart
 		bucket.Methods(http.MethodPut).Path("/{object:.+}").HandlerFunc(
-			m.Handle(metrics.APIStats("uploadpart", h.UploadPartHandler))).Queries("partNumber", "{partNumber:[0-9]+}", "uploadId", "{uploadId:.*}").
+			m.Handle(h.UploadPartHandler)).
+			Queries("partNumber", "{partNumber:[0-9]+}", "uploadId", "{uploadId:.*}").
 			Name("UploadPart")
 		// ListParts
 		bucket.Methods(http.MethodGet).Path("/{object:.+}").HandlerFunc(
-			m.Handle(metrics.APIStats("listobjectparts", h.ListPartsHandler))).Queries("uploadId", "{uploadId:.*}").
+			m.Handle(h.ListPartsHandler)).
+			Queries("uploadId", "{uploadId:.*}").
 			Name("ListObjectParts")
 		// CompleteMultipartUpload
 		bucket.Methods(http.MethodPost).Path("/{object:.+}").HandlerFunc(
-			m.Handle(metrics.APIStats("completemutipartupload", h.CompleteMultipartUploadHandler))).Queries("uploadId", "{uploadId:.*}").
+			m.Handle(h.CompleteMultipartUploadHandler)).
+			Queries("uploadId", "{uploadId:.*}").
 			Name("CompleteMultipartUpload")
 		// CreateMultipartUpload
 		bucket.Methods(http.MethodPost).Path("/{object:.+}").HandlerFunc(
-			m.Handle(metrics.APIStats("createmultipartupload", h.CreateMultipartUploadHandler))).Queries("uploads", "").
+			m.Handle(h.CreateMultipartUploadHandler)).
+			Queries("uploads", "").
 			Name("CreateMultipartUpload")
 		// AbortMultipartUpload
 		bucket.Methods(http.MethodDelete).Path("/{object:.+}").HandlerFunc(
-			m.Handle(metrics.APIStats("abortmultipartupload", h.AbortMultipartUploadHandler))).Queries("uploadId", "{uploadId:.*}").
+			m.Handle(h.AbortMultipartUploadHandler)).
+			Queries("uploadId", "{uploadId:.*}").
 			Name("AbortMultipartUpload")
 		// ListMultipartUploads
 		bucket.Methods(http.MethodGet).HandlerFunc(
-			m.Handle(metrics.APIStats("listmultipartuploads", h.ListMultipartUploadsHandler))).Queries("uploads", "").
+			m.Handle(h.ListMultipartUploadsHandler)).
+			Queries("uploads", "").
 			Name("ListMultipartUploads")
 		// GetObjectACL -- this is a dummy call.
 		bucket.Methods(http.MethodGet).Path("/{object:.+}").HandlerFunc(
-			m.Handle(metrics.APIStats("getobjectacl", h.GetObjectACLHandler))).Queries("acl", "").
+			m.Handle(h.GetObjectACLHandler)).
+			Queries("acl", "").
 			Name("GetObjectACL")
 		// PutObjectACL -- this is a dummy call.
 		bucket.Methods(http.MethodPut).Path("/{object:.+}").HandlerFunc(
-			m.Handle(metrics.APIStats("putobjectacl", h.PutObjectACLHandler))).Queries("acl", "").
+			m.Handle(h.PutObjectACLHandler)).
+			Queries("acl", "").
 			Name("PutObjectACL")
 		// GetObjectTagging
 		bucket.Methods(http.MethodGet).Path("/{object:.+}").HandlerFunc(
-			m.Handle(metrics.APIStats("getobjecttagging", h.GetObjectTaggingHandler))).Queries("tagging", "").
+			m.Handle(h.GetObjectTaggingHandler)).
+			Queries("tagging", "").
 			Name("GetObjectTagging")
 		// PutObjectTagging
 		bucket.Methods(http.MethodPut).Path("/{object:.+}").HandlerFunc(
-			m.Handle(metrics.APIStats("putobjecttagging", h.PutObjectTaggingHandler))).Queries("tagging", "").
+			m.Handle(h.PutObjectTaggingHandler)).
+			Queries("tagging", "").
 			Name("PutObjectTagging")
 		// DeleteObjectTagging
 		bucket.Methods(http.MethodDelete).Path("/{object:.+}").HandlerFunc(
-			m.Handle(metrics.APIStats("deleteobjecttagging", h.DeleteObjectTaggingHandler))).Queries("tagging", "").
+			m.Handle(h.DeleteObjectTaggingHandler)).
+			Queries("tagging", "").
 			Name("DeleteObjectTagging")
 		// SelectObjectContent
 		bucket.Methods(http.MethodPost).Path("/{object:.+}").HandlerFunc(
-			m.Handle(metrics.APIStats("selectobjectcontent", h.SelectObjectContentHandler))).Queries("select", "").Queries("select-type", "2").
+			m.Handle(h.SelectObjectContentHandler)).
+			Queries("select", "").Queries("select-type", "2").
 			Name("SelectObjectContent")
 		// GetObjectRetention
 		bucket.Methods(http.MethodGet).Path("/{object:.+}").HandlerFunc(
-			m.Handle(metrics.APIStats("getobjectretention", h.GetObjectRetentionHandler))).Queries("retention", "").
+			m.Handle(h.GetObjectRetentionHandler)).
+			Queries("retention", "").
 			Name("GetObjectRetention")
 		// GetObjectLegalHold
 		bucket.Methods(http.MethodGet).Path("/{object:.+}").HandlerFunc(
-			m.Handle(metrics.APIStats("getobjectlegalhold", h.GetObjectLegalHoldHandler))).Queries("legal-hold", "").
+			m.Handle(h.GetObjectLegalHoldHandler)).
+			Queries("legal-hold", "").
 			Name("GetObjectLegalHold")
 		// GetObjectAttributes
 		bucket.Methods(http.MethodGet).Path("/{object:.+}").HandlerFunc(
-			m.Handle(metrics.APIStats("getobjectattributes", h.GetObjectAttributesHandler))).Queries("attributes", "").
+			m.Handle(h.GetObjectAttributesHandler)).
+			Queries("attributes", "").
 			Name("GetObjectAttributes")
 		// GetObject
 		bucket.Methods(http.MethodGet).Path("/{object:.+}").HandlerFunc(
-			m.Handle(metrics.APIStats("getobject", h.GetObjectHandler))).
+			m.Handle(h.GetObjectHandler)).
 			Name("GetObject")
 		// CopyObject
-		bucket.Methods(http.MethodPut).Path("/{object:.+}").Headers(hdrAmzCopySource, "").HandlerFunc(m.Handle(metrics.APIStats("copyobject", h.CopyObjectHandler))).
+		bucket.Methods(http.MethodPut).Path("/{object:.+}").Headers(hdrAmzCopySource, "").HandlerFunc(
+			m.Handle(h.CopyObjectHandler)).
 			Name("CopyObject")
 		// PutObjectRetention
 		bucket.Methods(http.MethodPut).Path("/{object:.+}").HandlerFunc(
-			m.Handle(metrics.APIStats("putobjectretention", h.PutObjectRetentionHandler))).Queries("retention", "").
+			m.Handle(h.PutObjectRetentionHandler)).
+			Queries("retention", "").
 			Name("PutObjectRetention")
 		// PutObjectLegalHold
 		bucket.Methods(http.MethodPut).Path("/{object:.+}").HandlerFunc(
-			m.Handle(metrics.APIStats("putobjectlegalhold", h.PutObjectLegalHoldHandler))).Queries("legal-hold", "").
+			m.Handle(h.PutObjectLegalHoldHandler)).
+			Queries("legal-hold", "").
 			Name("PutObjectLegalHold")
 
 		// PutObject
 		bucket.Methods(http.MethodPut).Path("/{object:.+}").HandlerFunc(
-			m.Handle(metrics.APIStats("putobject", h.PutObjectHandler))).
+			m.Handle(h.PutObjectHandler)).
 			Name("PutObject")
 		// DeleteObject
 		bucket.Methods(http.MethodDelete).Path("/{object:.+}").HandlerFunc(
-			m.Handle(metrics.APIStats("deleteobject", h.DeleteObjectHandler))).
+			m.Handle(h.DeleteObjectHandler)).
 			Name("DeleteObject")
 
 		// Bucket operations
 		// GetBucketLocation
 		bucket.Methods(http.MethodGet).HandlerFunc(
-			m.Handle(metrics.APIStats("getbucketlocation", h.GetBucketLocationHandler))).Queries("location", "").
+			m.Handle(h.GetBucketLocationHandler)).
+			Queries("location", "").
 			Name("GetBucketLocation")
 		// GetBucketPolicy
 		bucket.Methods(http.MethodGet).HandlerFunc(
-			m.Handle(metrics.APIStats("getbucketpolicy", h.GetBucketPolicyHandler))).Queries("policy", "").
+			m.Handle(h.GetBucketPolicyHandler)).
+			Queries("policy", "").
 			Name("GetBucketPolicy")
 		// GetBucketLifecycle
 		bucket.Methods(http.MethodGet).HandlerFunc(
-			m.Handle(metrics.APIStats("getbucketlifecycle", h.GetBucketLifecycleHandler))).Queries("lifecycle", "").
+			m.Handle(h.GetBucketLifecycleHandler)).
+			Queries("lifecycle", "").
 			Name("GetBucketLifecycle")
 		// GetBucketEncryption
 		bucket.Methods(http.MethodGet).HandlerFunc(
-			m.Handle(metrics.APIStats("getbucketencryption", h.GetBucketEncryptionHandler))).Queries("encryption", "").
+			m.Handle(h.GetBucketEncryptionHandler)).
+			Queries("encryption", "").
 			Name("GetBucketEncryption")
 		bucket.Methods(http.MethodGet).HandlerFunc(
-			m.Handle(metrics.APIStats("getbucketcors", h.GetBucketCorsHandler))).Queries("cors", "").
+			m.Handle(h.GetBucketCorsHandler)).
+			Queries("cors", "").
 			Name("GetBucketCors")
 		bucket.Methods(http.MethodPut).HandlerFunc(
-			m.Handle(metrics.APIStats("putbucketcors", h.PutBucketCorsHandler))).Queries("cors", "").
+			m.Handle(h.PutBucketCorsHandler)).
+			Queries("cors", "").
 			Name("PutBucketCors")
 		bucket.Methods(http.MethodDelete).HandlerFunc(
-			m.Handle(metrics.APIStats("deletebucketcors", h.DeleteBucketCorsHandler))).Queries("cors", "").
+			m.Handle(h.DeleteBucketCorsHandler)).
+			Queries("cors", "").
 			Name("DeleteBucketCors")
 		// Dummy Bucket Calls
 		// GetBucketACL -- this is a dummy call.
 		bucket.Methods(http.MethodGet).HandlerFunc(
-			m.Handle(metrics.APIStats("getbucketacl", h.GetBucketACLHandler))).Queries("acl", "").
+			m.Handle(h.GetBucketACLHandler)).
+			Queries("acl", "").
 			Name("GetBucketACL")
 		// PutBucketACL -- this is a dummy call.
 		bucket.Methods(http.MethodPut).HandlerFunc(
-			m.Handle(metrics.APIStats("putbucketacl", h.PutBucketACLHandler))).Queries("acl", "").
+			m.Handle(h.PutBucketACLHandler)).
+			Queries("acl", "").
 			Name("PutBucketACL")
 		// GetBucketWebsiteHandler -- this is a dummy call.
 		bucket.Methods(http.MethodGet).HandlerFunc(
-			m.Handle(metrics.APIStats("getbucketwebsite", h.GetBucketWebsiteHandler))).Queries("website", "").
+			m.Handle(h.GetBucketWebsiteHandler)).
+			Queries("website", "").
 			Name("GetBucketWebsite")
 		// GetBucketAccelerateHandler -- this is a dummy call.
 		bucket.Methods(http.MethodGet).HandlerFunc(
-			m.Handle(metrics.APIStats("getbucketaccelerate", h.GetBucketAccelerateHandler))).Queries("accelerate", "").
+			m.Handle(h.GetBucketAccelerateHandler)).
+			Queries("accelerate", "").
 			Name("GetBucketAccelerate")
 		// GetBucketRequestPaymentHandler -- this is a dummy call.
 		bucket.Methods(http.MethodGet).HandlerFunc(
-			m.Handle(metrics.APIStats("getbucketrequestpayment", h.GetBucketRequestPaymentHandler))).Queries("requestPayment", "").
+			m.Handle(h.GetBucketRequestPaymentHandler)).
+			Queries("requestPayment", "").
 			Name("GetBucketRequestPayment")
 		// GetBucketLoggingHandler -- this is a dummy call.
 		bucket.Methods(http.MethodGet).HandlerFunc(
-			m.Handle(metrics.APIStats("getbucketlogging", h.GetBucketLoggingHandler))).Queries("logging", "").
+			m.Handle(h.GetBucketLoggingHandler)).
+			Queries("logging", "").
 			Name("GetBucketLogging")
-		// GetBucketLifecycleHandler -- this is a dummy call.
-		bucket.Methods(http.MethodGet).HandlerFunc(
-			m.Handle(metrics.APIStats("getbucketlifecycle", h.GetBucketLifecycleHandler))).Queries("lifecycle", "").
-			Name("GetBucketLifecycle")
 		// GetBucketReplicationHandler -- this is a dummy call.
 		bucket.Methods(http.MethodGet).HandlerFunc(
-			m.Handle(metrics.APIStats("getbucketreplication", h.GetBucketReplicationHandler))).Queries("replication", "").
+			m.Handle(h.GetBucketReplicationHandler)).
+			Queries("replication", "").
 			Name("GetBucketReplication")
 		// GetBucketTaggingHandler
 		bucket.Methods(http.MethodGet).HandlerFunc(
-			m.Handle(metrics.APIStats("getbuckettagging", h.GetBucketTaggingHandler))).Queries("tagging", "").
+			m.Handle(h.GetBucketTaggingHandler)).
+			Queries("tagging", "").
 			Name("GetBucketTagging")
 		// DeleteBucketWebsiteHandler
 		bucket.Methods(http.MethodDelete).HandlerFunc(
-			m.Handle(metrics.APIStats("deletebucketwebsite", h.DeleteBucketWebsiteHandler))).Queries("website", "").
+			m.Handle(h.DeleteBucketWebsiteHandler)).
+			Queries("website", "").
 			Name("DeleteBucketWebsite")
 		// DeleteBucketTaggingHandler
 		bucket.Methods(http.MethodDelete).HandlerFunc(
-			m.Handle(metrics.APIStats("deletebuckettagging", h.DeleteBucketTaggingHandler))).Queries("tagging", "").
+			m.Handle(h.DeleteBucketTaggingHandler)).
+			Queries("tagging", "").
 			Name("DeleteBucketTagging")
 
 		// GetBucketObjectLockConfig
 		bucket.Methods(http.MethodGet).HandlerFunc(
-			m.Handle(metrics.APIStats("getbucketobjectlockconfiguration", h.GetBucketObjectLockConfigHandler))).Queries("object-lock", "").
+			m.Handle(h.GetBucketObjectLockConfigHandler)).
+			Queries("object-lock", "").
 			Name("GetBucketObjectLockConfig")
 		// GetBucketVersioning
 		bucket.Methods(http.MethodGet).HandlerFunc(
-			m.Handle(metrics.APIStats("getbucketversioning", h.GetBucketVersioningHandler))).Queries("versioning", "").
+			m.Handle(h.GetBucketVersioningHandler)).
+			Queries("versioning", "").
 			Name("GetBucketVersioning")
 		// GetBucketNotification
 		bucket.Methods(http.MethodGet).HandlerFunc(
-			m.Handle(metrics.APIStats("getbucketnotification", h.GetBucketNotificationHandler))).Queries("notification", "").
+			m.Handle(h.GetBucketNotificationHandler)).
+			Queries("notification", "").
 			Name("GetBucketNotification")
 		// ListenBucketNotification
-		bucket.Methods(http.MethodGet).HandlerFunc(metrics.APIStats("listenbucketnotification", h.ListenBucketNotificationHandler)).Queries("events", "{events:.*}").
+		bucket.Methods(http.MethodGet).HandlerFunc(h.ListenBucketNotificationHandler).
+			Queries("events", "{events:.*}").
 			Name("ListenBucketNotification")
 		// ListObjectsV2M
 		bucket.Methods(http.MethodGet).HandlerFunc(
-			m.Handle(metrics.APIStats("listobjectsv2M", h.ListObjectsV2MHandler))).Queries("list-type", "2", "metadata", "true").
+			m.Handle(h.ListObjectsV2MHandler)).
+			Queries("list-type", "2", "metadata", "true").
 			Name("ListObjectsV2M")
 		// ListObjectsV2
 		bucket.Methods(http.MethodGet).HandlerFunc(
-			m.Handle(metrics.APIStats("listobjectsv2", h.ListObjectsV2Handler))).Queries("list-type", "2").
+			m.Handle(h.ListObjectsV2Handler)).
+			Queries("list-type", "2").
 			Name("ListObjectsV2")
 		// ListBucketVersions
 		bucket.Methods(http.MethodGet).HandlerFunc(
-			m.Handle(metrics.APIStats("listbucketversions", h.ListBucketObjectVersionsHandler))).Queries("versions", "").
+			m.Handle(h.ListBucketObjectVersionsHandler)).
+			Queries("versions", "").
 			Name("ListBucketVersions")
 		// ListObjectsV1 (Legacy)
 		bucket.Methods(http.MethodGet).HandlerFunc(
-			m.Handle(metrics.APIStats("listobjectsv1", h.ListObjectsV1Handler))).
+			m.Handle(h.ListObjectsV1Handler)).
 			Name("ListObjectsV1")
 		// PutBucketLifecycle
 		bucket.Methods(http.MethodPut).HandlerFunc(
-			m.Handle(metrics.APIStats("putbucketlifecycle", h.PutBucketLifecycleHandler))).Queries("lifecycle", "").
+			m.Handle(h.PutBucketLifecycleHandler)).
+			Queries("lifecycle", "").
 			Name("PutBucketLifecycle")
 		// PutBucketEncryption
 		bucket.Methods(http.MethodPut).HandlerFunc(
-			m.Handle(metrics.APIStats("putbucketencryption", h.PutBucketEncryptionHandler))).Queries("encryption", "").
+			m.Handle(h.PutBucketEncryptionHandler)).
+			Queries("encryption", "").
 			Name("PutBucketEncryption")
 
 		// PutBucketPolicy
 		bucket.Methods(http.MethodPut).HandlerFunc(
-			m.Handle(metrics.APIStats("putbucketpolicy", h.PutBucketPolicyHandler))).Queries("policy", "").
+			m.Handle(h.PutBucketPolicyHandler)).
+			Queries("policy", "").
 			Name("PutBucketPolicy")
 
 		// PutBucketObjectLockConfig
 		bucket.Methods(http.MethodPut).HandlerFunc(
-			m.Handle(metrics.APIStats("putbucketobjectlockconfig", h.PutBucketObjectLockConfigHandler))).Queries("object-lock", "").
+			m.Handle(h.PutBucketObjectLockConfigHandler)).
+			Queries("object-lock", "").
 			Name("PutBucketObjectLockConfig")
 		// PutBucketTaggingHandler
 		bucket.Methods(http.MethodPut).HandlerFunc(
-			m.Handle(metrics.APIStats("putbuckettagging", h.PutBucketTaggingHandler))).Queries("tagging", "").
+			m.Handle(h.PutBucketTaggingHandler)).
+			Queries("tagging", "").
 			Name("PutBucketTagging")
 		// PutBucketVersioning
 		bucket.Methods(http.MethodPut).HandlerFunc(
-			m.Handle(metrics.APIStats("putbucketversioning", h.PutBucketVersioningHandler))).Queries("versioning", "").
+			m.Handle(h.PutBucketVersioningHandler)).
+			Queries("versioning", "").
 			Name("PutBucketVersioning")
 		// PutBucketNotification
 		bucket.Methods(http.MethodPut).HandlerFunc(
-			m.Handle(metrics.APIStats("putbucketnotification", h.PutBucketNotificationHandler))).Queries("notification", "").
+			m.Handle(h.PutBucketNotificationHandler)).
+			Queries("notification", "").
 			Name("PutBucketNotification")
 		// CreateBucket
 		bucket.Methods(http.MethodPut).HandlerFunc(
-			m.Handle(metrics.APIStats("createbucket", h.CreateBucketHandler))).
+			m.Handle(h.CreateBucketHandler)).
 			Name("CreateBucket")
 		// HeadBucket
 		bucket.Methods(http.MethodHead).HandlerFunc(
-			m.Handle(metrics.APIStats("headbucket", h.HeadBucketHandler))).
+			m.Handle(h.HeadBucketHandler)).
 			Name("HeadBucket")
 		// PostPolicy
 		bucket.Methods(http.MethodPost).HeadersRegexp(hdrContentType, "multipart/form-data*").HandlerFunc(
-			m.Handle(metrics.APIStats("postobject", h.PostObject))).
+			m.Handle(h.PostObject)).
 			Name("PostObject")
 		// DeleteMultipleObjects
 		bucket.Methods(http.MethodPost).HandlerFunc(
-			m.Handle(metrics.APIStats("deletemultipleobjects", h.DeleteMultipleObjectsHandler))).Queries("delete", "").
+			m.Handle(h.DeleteMultipleObjectsHandler)).
+			Queries("delete", "").
 			Name("DeleteMultipleObjects")
 		// DeleteBucketPolicy
 		bucket.Methods(http.MethodDelete).HandlerFunc(
-			m.Handle(metrics.APIStats("deletebucketpolicy", h.DeleteBucketPolicyHandler))).Queries("policy", "").
+			m.Handle(h.DeleteBucketPolicyHandler)).
+			Queries("policy", "").
 			Name("DeleteBucketPolicy")
 		// DeleteBucketLifecycle
 		bucket.Methods(http.MethodDelete).HandlerFunc(
-			m.Handle(metrics.APIStats("deletebucketlifecycle", h.DeleteBucketLifecycleHandler))).Queries("lifecycle", "").
+			m.Handle(h.DeleteBucketLifecycleHandler)).
+			Queries("lifecycle", "").
 			Name("DeleteBucketLifecycle")
 		// DeleteBucketEncryption
 		bucket.Methods(http.MethodDelete).HandlerFunc(
-			m.Handle(metrics.APIStats("deletebucketencryption", h.DeleteBucketEncryptionHandler))).Queries("encryption", "").
+			m.Handle(h.DeleteBucketEncryptionHandler)).
+			Queries("encryption", "").
 			Name("DeleteBucketEncryption")
 		// DeleteBucket
 		bucket.Methods(http.MethodDelete).HandlerFunc(
-			m.Handle(metrics.APIStats("deletebucket", h.DeleteBucketHandler))).
+			m.Handle(h.DeleteBucketHandler)).
 			Name("DeleteBucket")
 	}
 	// Root operation
 
 	// ListBuckets
 	api.Methods(http.MethodGet).Path(SlashSeparator).HandlerFunc(
-		m.Handle(metrics.APIStats("listbuckets", h.ListBucketsHandler))).
+		m.Handle(h.ListBucketsHandler)).
 		Name("ListBuckets")
 
 	// S3 browser with signature v4 adds '//' for ListBuckets request, so rather
 	// than failing with UnknownAPIRequest we simply handle it for now.
 	api.Methods(http.MethodGet).Path(SlashSeparator + SlashSeparator).HandlerFunc(
-		m.Handle(metrics.APIStats("listbuckets", h.ListBucketsHandler))).
+		m.Handle(h.ListBucketsHandler)).
 		Name("ListBuckets")
-
-	// If none of the routes match, add default error handler routes
-	api.NotFoundHandler = metrics.APIStats("notfound", errorResponseHandler)
-	api.MethodNotAllowedHandler = metrics.APIStats("methodnotallowed", errorResponseHandler)
 }
diff --git a/api/user_auth.go b/api/user_auth.go
index 911621e..938b469 100644
--- a/api/user_auth.go
+++ b/api/user_auth.go
@@ -19,9 +19,9 @@ var BoxData = KeyWrapper("__context_box_key")
 // ClientTime is an ID used to store client time.Time in a context.
 var ClientTime = KeyWrapper("__context_client_time")
 
-// AttachUserAuth adds user authentication via center to router using log for logging.
-func AttachUserAuth(router *mux.Router, center auth.Center, log *zap.Logger) {
-	router.Use(func(h http.Handler) http.Handler {
+// AuthMiddleware adds user authentication via center to router using log for logging.
+func AuthMiddleware(log *zap.Logger, center auth.Center) mux.MiddlewareFunc {
+	return func(h http.Handler) http.Handler {
 		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 			var ctx context.Context
 			box, err := center.Authenticate(r)
@@ -46,5 +46,5 @@ func AttachUserAuth(router *mux.Router, center auth.Center, log *zap.Logger) {
 
 			h.ServeHTTP(w, r.WithContext(ctx))
 		})
-	})
+	}
 }