diff --git a/api/handler/copy.go b/api/handler/copy.go
index 3468159a..460c93e7 100644
--- a/api/handler/copy.go
+++ b/api/handler/copy.go
@@ -81,7 +81,7 @@ func (h *handler) CopyObjectHandler(w http.ResponseWriter, r *http.Request) {
 		}, r.URL)
 
 		return
-	} else if err = api.EncodeToResponse(w, &CopyObjectResponse{LastModified: inf.Created.Format(time.RFC3339)}); err != nil {
+	} else if err = api.EncodeToResponse(w, &CopyObjectResponse{LastModified: inf.Created.Format(time.RFC3339), ETag: inf.HashSum}); err != nil {
 		h.log.Error("something went wrong",
 			zap.String("request_id", rid),
 			zap.String("dst_bucket_name", bkt),
diff --git a/api/handler/get.go b/api/handler/get.go
index 65f0487d..5113ad85 100644
--- a/api/handler/get.go
+++ b/api/handler/get.go
@@ -1,13 +1,10 @@
 package handler
 
 import (
-	"context"
 	"fmt"
-	"io"
 	"net/http"
 	"strconv"
 	"strings"
-	"sync"
 
 	"github.com/gorilla/mux"
 	"github.com/nspcc-dev/neofs-s3-gw/api"
@@ -15,61 +12,6 @@ import (
 	"go.uber.org/zap"
 )
 
-type (
-	detector struct {
-		io.Writer
-		sync.Once
-
-		contentType string
-	}
-)
-
-func newDetector(w io.Writer) *detector {
-	return &detector{Writer: w}
-}
-
-func (d *detector) Write(data []byte) (int, error) {
-	d.Once.Do(func() {
-		if rw, ok := d.Writer.(http.ResponseWriter); ok {
-			rw.WriteHeader(http.StatusOK)
-		}
-
-		d.contentType = http.DetectContentType(data)
-	})
-
-	return d.Writer.Write(data)
-}
-
-func (h *handler) contentTypeFetcher(ctx context.Context, w io.Writer, info *layer.ObjectInfo) (string, error) {
-	return h.contentTypeFetcherWithRange(ctx, w, info, nil)
-}
-
-func (h *handler) contentTypeFetcherWithRange(ctx context.Context, w io.Writer, info *layer.ObjectInfo, rangeParams *layer.RangeParams) (string, error) {
-	if info.IsDir() {
-		if rangeParams != nil {
-			return "", fmt.Errorf("it is forbidden to request for a range in the directory")
-		}
-		return info.ContentType, nil
-	}
-
-	writer := newDetector(w)
-
-	params := &layer.GetObjectParams{
-		Bucket: info.Bucket,
-		Object: info.Name,
-		Writer: writer,
-		Range:  rangeParams,
-	}
-
-	// params.Length = inf.Size
-
-	if err := h.obj.GetObject(ctx, params); err != nil {
-		return "", err
-	}
-
-	return writer.contentType, nil
-}
-
 func fetchRangeHeader(headers http.Header, fullSize uint64) (*layer.RangeParams, error) {
 	const prefix = "bytes="
 	rangeHeader := headers.Get("Range")
@@ -107,9 +49,12 @@ func fetchRangeHeader(headers http.Header, fullSize uint64) (*layer.RangeParams,
 }
 
 func writeHeaders(h http.Header, info *layer.ObjectInfo) {
-	h.Set("Content-Type", info.ContentType)
-	h.Set("Last-Modified", info.Created.Format(http.TimeFormat))
-	h.Set("Content-Length", strconv.FormatInt(info.Size, 10))
+	if len(info.ContentType) > 0 {
+		h.Set(api.ContentType, info.ContentType)
+	}
+	h.Set(api.LastModified, info.Created.Format(http.TimeFormat))
+	h.Set(api.ContentLength, strconv.FormatInt(info.Size, 10))
+	h.Set(api.ETag, info.HashSum)
 
 	for key, val := range info.Headers {
 		h.Set("X-"+key, val)
@@ -136,15 +81,20 @@ func (h *handler) GetObjectHandler(w http.ResponseWriter, r *http.Request) {
 		writeError(w, r, h.log, "could not parse range header", rid, bkt, obj, err)
 		return
 	}
-	if inf.ContentType, err = h.contentTypeFetcherWithRange(r.Context(), w, inf, params); err != nil {
-		writeError(w, r, h.log, "could not get object", rid, bkt, obj, err)
-		return
-	}
-
 	writeHeaders(w.Header(), inf)
 	if params != nil {
 		writeRangeHeaders(w, params, inf.Size)
 	}
+
+	getParams := &layer.GetObjectParams{
+		Bucket: inf.Bucket,
+		Object: inf.Name,
+		Writer: w,
+		Range:  params,
+	}
+	if err = h.obj.GetObject(r.Context(), getParams); err != nil {
+		writeError(w, r, h.log, "could not get object", rid, bkt, obj, err)
+	}
 }
 
 func writeRangeHeaders(w http.ResponseWriter, params *layer.RangeParams, size int64) {
diff --git a/api/handler/head.go b/api/handler/head.go
index 0b335dad..e3b75806 100644
--- a/api/handler/head.go
+++ b/api/handler/head.go
@@ -1,6 +1,7 @@
 package handler
 
 import (
+	"bytes"
 	"context"
 	"net/http"
 
@@ -12,10 +13,18 @@ import (
 	"google.golang.org/grpc/status"
 )
 
-type devNull int
+const sizeToDetectType = 512
 
-func (d devNull) Write(p []byte) (n int, err error) {
-	return len(p), nil
+func getRangeToDetectContentType(maxSize int64) *layer.RangeParams {
+	end := uint64(maxSize)
+	if sizeToDetectType < end {
+		end = sizeToDetectType
+	}
+
+	return &layer.RangeParams{
+		Start: 0,
+		End:   end - 1,
+	}
 }
 
 func (h *handler) checkIsFolder(ctx context.Context, bucket, object string) *layer.ObjectInfo {
@@ -73,7 +82,15 @@ func (h *handler) HeadObjectHandler(w http.ResponseWriter, r *http.Request) {
 		}, r.URL)
 
 		return
-	} else if inf.ContentType, err = h.contentTypeFetcher(r.Context(), devNull(0), inf); err != nil {
+	}
+	buffer := bytes.NewBuffer(make([]byte, 0, sizeToDetectType))
+	getParams := &layer.GetObjectParams{
+		Bucket: inf.Bucket,
+		Object: inf.Name,
+		Writer: buffer,
+		Range:  getRangeToDetectContentType(inf.Size),
+	}
+	if err = h.obj.GetObject(r.Context(), getParams); err != nil {
 		h.log.Error("could not get object",
 			zap.String("request_id", rid),
 			zap.String("bucket_name", bkt),
@@ -89,7 +106,7 @@ func (h *handler) HeadObjectHandler(w http.ResponseWriter, r *http.Request) {
 
 		return
 	}
-
+	inf.ContentType = http.DetectContentType(buffer.Bytes())
 	writeHeaders(w.Header(), inf)
 	w.WriteHeader(http.StatusOK)
 }
diff --git a/api/handler/list.go b/api/handler/list.go
index a05257fb..3212f49b 100644
--- a/api/handler/list.go
+++ b/api/handler/list.go
@@ -196,7 +196,7 @@ func encodeV1(arg *listObjectsArgs, list *layer.ListObjectsInfo) *ListObjectsRes
 				DisplayName: obj.Owner.String(),
 			},
 
-			// ETag:         "",
+			ETag: obj.HashSum,
 			// StorageClass: "",
 		})
 	}
@@ -259,7 +259,7 @@ func encodeV2(arg *listObjectsArgs, list *layer.ListObjectsInfo) *ListObjectsV2R
 				DisplayName: obj.Owner.String(),
 			},
 
-			// ETag:         "",
+			ETag: obj.HashSum,
 			// StorageClass: "",
 		})
 	}
diff --git a/api/handler/put.go b/api/handler/put.go
index 2df676eb..cae8a8df 100644
--- a/api/handler/put.go
+++ b/api/handler/put.go
@@ -24,11 +24,12 @@ const (
 
 func (h *handler) PutObjectHandler(w http.ResponseWriter, r *http.Request) {
 	var (
-		err error
-		req = mux.Vars(r)
-		bkt = req["bucket"]
-		obj = req["object"]
-		rid = api.GetRequestID(r.Context())
+		err  error
+		info *layer.ObjectInfo
+		req  = mux.Vars(r)
+		bkt  = req["bucket"]
+		obj  = req["object"]
+		rid  = api.GetRequestID(r.Context())
 	)
 
 	if _, err := h.obj.GetBucketInfo(r.Context(), bkt); err != nil {
@@ -53,7 +54,7 @@ func (h *handler) PutObjectHandler(w http.ResponseWriter, r *http.Request) {
 		Size:   r.ContentLength,
 	}
 
-	if _, err = h.obj.PutObject(r.Context(), params); err != nil {
+	if info, err = h.obj.PutObject(r.Context(), params); err != nil {
 		h.log.Error("could not upload object",
 			zap.String("request_id", rid),
 			zap.String("bucket_name", bkt),
@@ -69,6 +70,7 @@ func (h *handler) PutObjectHandler(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
+	w.Header().Set(api.ETag, info.HashSum)
 	api.WriteSuccessResponseHeadersOnly(w)
 }
 
diff --git a/api/layer/object.go b/api/layer/object.go
index 738d2bd0..4fe56f92 100644
--- a/api/layer/object.go
+++ b/api/layer/object.go
@@ -142,6 +142,14 @@ func (n *layer) objectPut(ctx context.Context, p *PutObjectParams) (*ObjectInfo,
 		return nil, err
 	}
 
+	addr := object.NewAddress()
+	addr.SetObjectID(oid)
+	addr.SetContainerID(bkt.CID)
+	meta, err := n.objectHead(ctx, addr)
+	if err != nil {
+		return nil, err
+	}
+
 	return &ObjectInfo{
 		id: oid,
 
@@ -152,6 +160,7 @@ func (n *layer) objectPut(ctx context.Context, p *PutObjectParams) (*ObjectInfo,
 		Created:     time.Now(),
 		Headers:     p.Header,
 		ContentType: r.contentType,
+		HashSum:     meta.PayloadChecksum().String(),
 	}, nil
 }
 
diff --git a/api/layer/util.go b/api/layer/util.go
index 90f9ddb4..1b1c70af 100644
--- a/api/layer/util.go
+++ b/api/layer/util.go
@@ -1,7 +1,6 @@
 package layer
 
 import (
-	"net/http"
 	"os"
 	"strconv"
 	"strings"
@@ -22,6 +21,7 @@ type (
 		Size        int64
 		ContentType string
 		Created     time.Time
+		HashSum     string
 		Owner       *owner.ID
 		Headers     map[string]string
 	}
@@ -102,10 +102,10 @@ func objectInfoFromMeta(bkt *BucketInfo, meta *object.Object, prefix, delimiter
 			filename = prefix + tail[:index+1]
 			userHeaders = nil
 		} else {
-			size, mimeType = getSizeAndMimeType(meta, mimeType)
+			size = int64(meta.PayloadSize())
 		}
 	} else {
-		size, mimeType = getSizeAndMimeType(meta, mimeType)
+		size = int64(meta.PayloadSize())
 	}
 
 	return &ObjectInfo{
@@ -119,18 +119,10 @@ func objectInfoFromMeta(bkt *BucketInfo, meta *object.Object, prefix, delimiter
 		Headers:     userHeaders,
 		Owner:       meta.OwnerID(),
 		Size:        size,
+		HashSum:     meta.PayloadChecksum().String(),
 	}
 }
 
-func getSizeAndMimeType(meta *object.Object, contentType string) (size int64, mimeType string) {
-	size = int64(meta.PayloadSize())
-	mimeType = contentType
-	if len(mimeType) == 0 {
-		mimeType = http.DetectContentType(meta.Payload())
-	}
-	return
-}
-
 func filenameFromObject(o *object.Object) string {
 	var name = o.ID().String()
 	for _, attr := range o.Attributes() {