diff --git a/api/auth/center.go b/api/auth/center.go
index 59a36f811..2aca7b6cc 100644
--- a/api/auth/center.go
+++ b/api/auth/center.go
@@ -24,6 +24,7 @@ import (
 var authorizationFieldRegexp = regexp.MustCompile(`AWS4-HMAC-SHA256 Credential=(?P<access_key_id_cid>[^/]+)/(?P<access_key_id_oid>[^/]+)/(?P<date>[^/]+)/(?P<region>[^/]*)/(?P<service>[^/]+)/aws4_request,\s*SignedHeaders=(?P<signed_header_fields>.+),\s*Signature=(?P<v4_signature>.+)`)
 
 type (
+	// Center is a user authentication interface.
 	Center interface {
 		Authenticate(request *http.Request) (*token.BearerToken, error)
 	}
@@ -33,6 +34,7 @@ type (
 		cli bearer.Credentials
 	}
 
+	// Params stores node connection parameters.
 	Params struct {
 		Client     sdk.Client
 		Logger     *zap.Logger
diff --git a/api/handler/api.go b/api/handler/api.go
index bdea9147c..293a27c8d 100644
--- a/api/handler/api.go
+++ b/api/handler/api.go
@@ -14,6 +14,7 @@ type (
 		obj layer.Client
 	}
 
+	// Params holds logger and client.
 	Params struct {
 		Log *zap.Logger
 		Obj layer.Client
@@ -24,6 +25,7 @@ const notSupported = "Not supported by NeoFS S3 Gate: "
 
 var _ api.Handler = (*handler)(nil)
 
+// New creates new api.Handler using given logger and client.
 func New(log *zap.Logger, obj layer.Client) (api.Handler, error) {
 	switch {
 	case obj == nil:
diff --git a/api/handler/list.go b/api/handler/list.go
index 972ebf007..452f0f7de 100644
--- a/api/handler/list.go
+++ b/api/handler/list.go
@@ -22,12 +22,14 @@ type listObjectsArgs struct {
 	Version   string
 }
 
+// VersioningConfiguration contains VersioningConfiguration XML representation.
 type VersioningConfiguration struct {
 	XMLName xml.Name `xml:"VersioningConfiguration"`
 	Text    string   `xml:",chardata"`
 	Xmlns   string   `xml:"xmlns,attr"`
 }
 
+// ListMultipartUploadsResult contains ListMultipartUploadsResult XML representation.
 type ListMultipartUploadsResult struct {
 	XMLName xml.Name `xml:"ListMultipartUploadsResult"`
 	Text    string   `xml:",chardata"`
@@ -36,6 +38,7 @@ type ListMultipartUploadsResult struct {
 
 var maxObjectList = 10000 // Limit number of objects in a listObjectsResponse/listObjectsVersionsResponse.
 
+// ListBucketsHandler handles bucket listing requests.
 func (h *handler) ListBucketsHandler(w http.ResponseWriter, r *http.Request) {
 	var (
 		err error
@@ -134,6 +137,7 @@ func (h *handler) listObjects(w http.ResponseWriter, r *http.Request) (*listObje
 	return arg, list, nil
 }
 
+// ListObjectsV1Handler handles objects listing requests for API version 1.
 func (h *handler) ListObjectsV1Handler(w http.ResponseWriter, r *http.Request) {
 	var rid = api.GetRequestID(r.Context())
 	if arg, list, err := h.listObjects(w, r); err != nil {
@@ -193,6 +197,7 @@ func encodeV1(arg *listObjectsArgs, list *layer.ListObjectsInfo) *ListObjectsRes
 	return res
 }
 
+// ListObjectsV2Handler handles objects listing requests for API version 2.
 func (h *handler) ListObjectsV2Handler(w http.ResponseWriter, r *http.Request) {
 	var rid = api.GetRequestID(r.Context())
 	if arg, list, err := h.listObjects(w, r); err != nil {
@@ -278,6 +283,7 @@ func parseListObjectArgs(r *http.Request) (*listObjectsArgs, error) {
 	return &res, nil
 }
 
+// GetBucketVersioningHandler implements bucket versioning getter handler.
 func (h *handler) GetBucketVersioningHandler(w http.ResponseWriter, r *http.Request) {
 	var (
 		rid = api.GetRequestID(r.Context())
@@ -299,6 +305,7 @@ func (h *handler) GetBucketVersioningHandler(w http.ResponseWriter, r *http.Requ
 	}
 }
 
+// ListMultipartUploadsHandler implements multipart uploads listing handler.
 func (h *handler) ListMultipartUploadsHandler(w http.ResponseWriter, r *http.Request) {
 	var (
 		rid = api.GetRequestID(r.Context())
diff --git a/api/layer/container.go b/api/layer/container.go
index bdfe3e1b2..5138a4d0f 100644
--- a/api/layer/container.go
+++ b/api/layer/container.go
@@ -12,6 +12,7 @@ import (
 )
 
 type (
+	// BucketInfo stores basic bucket data.
 	BucketInfo struct {
 		Name    string
 		CID     *container.ID
@@ -19,6 +20,7 @@ type (
 		Created time.Time
 	}
 
+	// ListObjectsParams represents object listing request parameters.
 	ListObjectsParams struct {
 		Bucket    string
 		Prefix    string
diff --git a/api/layer/layer.go b/api/layer/layer.go
index 927c02797..46b1144e4 100644
--- a/api/layer/layer.go
+++ b/api/layer/layer.go
@@ -25,6 +25,7 @@ type (
 		log *zap.Logger
 	}
 
+	// Params stores basic API parameters.
 	Params struct {
 		Pool       pool.Client
 		Logger     *zap.Logger
@@ -32,6 +33,7 @@ type (
 		Credential neofs.Credentials
 	}
 
+	// GetObjectParams stores object get request parameters.
 	GetObjectParams struct {
 		Bucket string
 		Object string
@@ -40,6 +42,7 @@ type (
 		Writer io.Writer
 	}
 
+	// PutObjectParams stores object put request parameters.
 	PutObjectParams struct {
 		Bucket string
 		Object string
@@ -48,6 +51,7 @@ type (
 		Header map[string]string
 	}
 
+	// CopyObjectParams stores object copy request parameters.
 	CopyObjectParams struct {
 		SrcBucket string
 		DstBucket string
@@ -56,10 +60,12 @@ type (
 		Header    map[string]string
 	}
 
+	// NeoFS provides basic NeoFS interface.
 	NeoFS interface {
 		Get(ctx context.Context, address *object.Address) (*object.Object, error)
 	}
 
+	// Client provides S3 API client interface.
 	Client interface {
 		NeoFS
 
@@ -81,11 +87,13 @@ type (
 )
 
 var (
-	ErrObjectExists    = errors.New("object exists")
+	// ErrObjectExists is returned on attempts to create already existing object.
+	ErrObjectExists = errors.New("object exists")
+	// ErrObjectNotExists is returned on attempts to work with non-existing object.
 	ErrObjectNotExists = errors.New("object not exists")
 )
 
-// NewGatewayLayer creates instance of layer. It checks credentials
+// NewLayer creates instance of layer. It checks credentials
 // and establishes gRPC connection with node.
 func NewLayer(log *zap.Logger, cli sdk.Client) Client {
 	return &layer{
diff --git a/api/layer/util.go b/api/layer/util.go
index 014eed896..966560955 100644
--- a/api/layer/util.go
+++ b/api/layer/util.go
@@ -12,6 +12,7 @@ import (
 )
 
 type (
+	// ObjectInfo holds S3 object data.
 	ObjectInfo struct {
 		id    *object.ID
 		isDir bool
@@ -52,6 +53,7 @@ type (
 
 const (
 	rootSeparator = "root://"
+	// PathSeparator is a path components separator string.
 	PathSeparator = string(os.PathSeparator)
 )
 
@@ -140,11 +142,14 @@ func nameFromObject(o *object.Object) (string, string) {
 	return NameFromString(name)
 }
 
+// NameFromString splits name into base file name and directory path.
 func NameFromString(name string) (string, string) {
 	ind := strings.LastIndex(name, PathSeparator)
 	return name[ind+1:], name[:ind+1]
 }
 
+// ID returns object ID from ObjectInfo.
 func (o *ObjectInfo) ID() *object.ID { return o.id }
 
+// IsDir allows to check if object is a directory.
 func (o *ObjectInfo) IsDir() bool { return o.isDir }
diff --git a/api/max-clients.go b/api/max-clients.go
index 93902f044..f2eb25708 100644
--- a/api/max-clients.go
+++ b/api/max-clients.go
@@ -6,6 +6,7 @@ import (
 )
 
 type (
+	// MaxClients provides HTTP handler wrapper with client limit.
 	MaxClients interface {
 		Handle(http.HandlerFunc) http.HandlerFunc
 	}
@@ -18,6 +19,8 @@ type (
 
 const defaultRequestDeadline = time.Second * 30
 
+// NewMaxClientsMiddleware returns MaxClients interface with handler wrapper based on
+// provided count and timeout limits.
 func NewMaxClientsMiddleware(count int, timeout time.Duration) MaxClients {
 	if timeout <= 0 {
 		timeout = defaultRequestDeadline
@@ -29,6 +32,7 @@ func NewMaxClientsMiddleware(count int, timeout time.Duration) MaxClients {
 	}
 }
 
+// Handler wraps HTTP handler function with logic limiting access to it.
 func (m *maxClients) Handle(f http.HandlerFunc) http.HandlerFunc {
 	return func(w http.ResponseWriter, r *http.Request) {
 		if m.pool == nil {
diff --git a/api/metrics/api.go b/api/metrics/api.go
index 56b406389..503cb171c 100644
--- a/api/metrics/api.go
+++ b/api/metrics/api.go
@@ -103,6 +103,7 @@ func collectHTTPMetrics(ch chan<- prometheus.Metric) {
 	}
 }
 
+// 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)
diff --git a/api/reqinfo.go b/api/reqinfo.go
index 374a13083..c6594e1f2 100644
--- a/api/reqinfo.go
+++ b/api/reqinfo.go
@@ -33,6 +33,7 @@ type (
 		tags         []KeyVal // Any additional info not accommodated by above fields
 	}
 
+	// ObjectRequest represents object request data.
 	ObjectRequest struct {
 		Bucket string
 		Object string
diff --git a/api/response.go b/api/response.go
index 872eeac1f..33b34109c 100644
--- a/api/response.go
+++ b/api/response.go
@@ -36,7 +36,7 @@ type (
 		StatusCode int `xml:"-" json:"-"`
 	}
 
-	// APIError structure.
+	// Error structure represents API error.
 	Error struct {
 		Code           string
 		Description    string
@@ -168,6 +168,7 @@ func removeSensitiveHeaders(h http.Header) {
 	h.Del(hdrSSECopyKey)
 }
 
+// WriteResponse writes given statusCode and response into w (with mType header if set).
 func WriteResponse(w http.ResponseWriter, statusCode int, response []byte, mType mimeType) {
 	setCommonHeaders(w)
 	if mType != MimeNone {
@@ -214,6 +215,8 @@ func EncodeToResponse(w http.ResponseWriter, response interface{}) error {
 // 	WriteResponse(w, http.StatusOK, response, MimeXML)
 // }
 
+// WriteSuccessResponseHeadersOnly writes HTTP (200) OK response with no data
+// to the client.
 func WriteSuccessResponseHeadersOnly(w http.ResponseWriter) {
 	WriteResponse(w, http.StatusOK, nil, MimeNone)
 }
diff --git a/api/router.go b/api/router.go
index 6291a4442..8ae7b65b3 100644
--- a/api/router.go
+++ b/api/router.go
@@ -14,6 +14,7 @@ import (
 )
 
 type (
+	// Handler is an S3 API handler interface.
 	Handler interface {
 		HeadObjectHandler(http.ResponseWriter, *http.Request)
 		CopyObjectPartHandler(http.ResponseWriter, *http.Request)
@@ -158,6 +159,7 @@ func logErrorResponse(l *zap.Logger) mux.MiddlewareFunc {
 	}
 }
 
+// GetRequestID returns request ID from response writer or context.
 func GetRequestID(v interface{}) string {
 	switch t := v.(type) {
 	case context.Context:
@@ -169,6 +171,8 @@ func GetRequestID(v interface{}) string {
 	}
 }
 
+// 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) {
 	api := r.PathPrefix(SlashSeparator).Subrouter()
 
diff --git a/api/user-auth.go b/api/user-auth.go
index ceaa6b9eb..4baaffb6d 100644
--- a/api/user-auth.go
+++ b/api/user-auth.go
@@ -9,6 +9,7 @@ import (
 	"go.uber.org/zap"
 )
 
+// 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 {
 		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
diff --git a/cmd/gate/app-healthy.go b/cmd/gate/app-healthy.go
index 576fe4db6..ca487a93e 100644
--- a/cmd/gate/app-healthy.go
+++ b/cmd/gate/app-healthy.go
@@ -7,6 +7,7 @@ import (
 	"github.com/gorilla/mux"
 )
 
+// Healthy is a health check interface.
 type Healthy interface {
 	Status() error
 }
diff --git a/cmd/gate/app.go b/cmd/gate/app.go
index 955eb6613..474bd4ada 100644
--- a/cmd/gate/app.go
+++ b/cmd/gate/app.go
@@ -22,6 +22,7 @@ import (
 )
 
 type (
+	// App is the main application structure.
 	App struct {
 		cli pool.Client
 		ctr auth.Center
@@ -179,6 +180,7 @@ func newApp(ctx context.Context, l *zap.Logger, v *viper.Viper) *App {
 	}
 }
 
+// Wait waits for application to finish.
 func (a *App) Wait() {
 	a.log.Info("application started")
 
@@ -192,6 +194,7 @@ func (a *App) Wait() {
 	a.log.Info("application finished")
 }
 
+// Server runs HTTP server to handle S3 API requests.
 func (a *App) Server(ctx context.Context) {
 	var (
 		err  error
@@ -256,6 +259,7 @@ func (a *App) Server(ctx context.Context) {
 	close(a.webDone)
 }
 
+// Worker runs client worker.
 func (a *App) Worker(ctx context.Context) {
 	a.cli.Worker(ctx)
 	a.log.Info("stopping worker")
diff --git a/misc/build.go b/misc/build.go
index c014aacad..c954d3554 100644
--- a/misc/build.go
+++ b/misc/build.go
@@ -1,12 +1,16 @@
 package misc
 
 const (
+	// ApplicationName is gateway name.
 	ApplicationName = "neofs-s3-gate"
 
+	// Prefix is configuration environment variables prefix.
 	Prefix = "S3_GW"
 )
 
 var (
-	Build   = "now"
+	// Build holds build timestamp.
+	Build = "now"
+	// Version contains application version.
 	Version = "dev"
 )