diff --git a/internal/aghhttp/aghhttp.go b/internal/aghhttp/aghhttp.go
index 57a1c868..64e31075 100644
--- a/internal/aghhttp/aghhttp.go
+++ b/internal/aghhttp/aghhttp.go
@@ -6,6 +6,7 @@ import (
 	"io"
 	"net/http"
 
+	"github.com/AdguardTeam/AdGuardHome/internal/version"
 	"github.com/AdguardTeam/golibs/log"
 )
 
@@ -28,3 +29,9 @@ func Error(r *http.Request, w http.ResponseWriter, code int, format string, args
 	log.Error("%s %s: %s", r.Method, r.URL, text)
 	http.Error(w, text, code)
 }
+
+// UserAgent returns the ID of the service as a User-Agent string.  It can also
+// be used as the value of the Server HTTP header.
+func UserAgent() (ua string) {
+	return fmt.Sprintf("AdGuardDNS/%s", version.Version())
+}
diff --git a/internal/aghhttp/header.go b/internal/aghhttp/header.go
new file mode 100644
index 00000000..87a18396
--- /dev/null
+++ b/internal/aghhttp/header.go
@@ -0,0 +1,21 @@
+package aghhttp
+
+// HTTP Headers
+
+// HTTP header name constants.
+//
+// TODO(a.garipov): Remove unused.
+const (
+	HdrNameAcceptEncoding           = "Accept-Encoding"
+	HdrNameAccessControlAllowOrigin = "Access-Control-Allow-Origin"
+	HdrNameContentType              = "Content-Type"
+	HdrNameContentEncoding          = "Content-Encoding"
+	HdrNameServer                   = "Server"
+	HdrNameTrailer                  = "Trailer"
+	HdrNameUserAgent                = "User-Agent"
+)
+
+// HTTP header value constants.
+const (
+	HdrValApplicationJSON = "application/json"
+)
diff --git a/internal/next/websvc/json.go b/internal/next/websvc/json.go
index 15b2f7e2..4b35c694 100644
--- a/internal/next/websvc/json.go
+++ b/internal/next/websvc/json.go
@@ -8,11 +8,15 @@ import (
 	"strconv"
 	"time"
 
+	"github.com/AdguardTeam/AdGuardHome/internal/aghhttp"
 	"github.com/AdguardTeam/golibs/log"
 )
 
 // JSON Utilities
 
+// nsecPerMsec is the number of nanoseconds in a millisecond.
+const nsecPerMsec = float64(time.Millisecond / time.Nanosecond)
+
 // JSONDuration is a time.Duration that can be decoded from JSON and encoded
 // into JSON according to our API conventions.
 type JSONDuration time.Duration
@@ -55,9 +59,6 @@ type JSONTime time.Time
 // type check
 var _ json.Marshaler = JSONTime{}
 
-// nsecPerMsec is the number of nanoseconds in a millisecond.
-const nsecPerMsec = float64(time.Millisecond / time.Nanosecond)
-
 // MarshalJSON implements the json.Marshaler interface for JSONTime.  err is
 // always nil.
 func (t JSONTime) MarshalJSON() (b []byte, err error) {
@@ -88,7 +89,12 @@ func (t *JSONTime) UnmarshalJSON(b []byte) (err error) {
 
 // writeJSONResponse encodes v into w and logs any errors it encounters.  r is
 // used to get additional information from the request.
-func writeJSONResponse(w io.Writer, r *http.Request, v any) {
+func writeJSONResponse(w http.ResponseWriter, r *http.Request, v any) {
+	// TODO(a.garipov): Put some of these to a middleware.
+	h := w.Header()
+	h.Set(aghhttp.HdrNameContentType, aghhttp.HdrValApplicationJSON)
+	h.Set(aghhttp.HdrNameServer, aghhttp.UserAgent())
+
 	err := json.NewEncoder(w).Encode(v)
 	if err != nil {
 		log.Error("websvc: writing resp to %s %s: %s", r.Method, r.URL.Path, err)
diff --git a/internal/version/version.go b/internal/version/version.go
index 2091d859..ca78efff 100644
--- a/internal/version/version.go
+++ b/internal/version/version.go
@@ -63,14 +63,6 @@ func Version() (v string) {
 	return version
 }
 
-// Constants defining the format of module information string.
-const (
-	modInfoAtSep    = "@"
-	modInfoDevSep   = " "
-	modInfoSumLeft  = " (sum: "
-	modInfoSumRight = ")"
-)
-
 // fmtModule returns formatted information about module.  The result looks like:
 //
 //	github.com/Username/module@v1.2.3 (sum: someHASHSUM=)
@@ -87,14 +79,16 @@ func fmtModule(m *debug.Module) (formatted string) {
 
 	stringutil.WriteToBuilder(b, m.Path)
 	if ver := m.Version; ver != "" {
-		sep := modInfoAtSep
+		sep := "@"
 		if ver == "(devel)" {
-			sep = modInfoDevSep
+			sep = " "
 		}
+
 		stringutil.WriteToBuilder(b, sep, ver)
 	}
+
 	if sum := m.Sum; sum != "" {
-		stringutil.WriteToBuilder(b, modInfoSumLeft, sum, modInfoSumRight)
+		stringutil.WriteToBuilder(b, "(sum: ", sum, ")")
 	}
 
 	return b.String()