diff --git a/trading_assistant_api/common/types/response.go b/trading_assistant_api/common/types/response.go
index 29ab357..c5e5f0e 100644
--- a/trading_assistant_api/common/types/response.go
+++ b/trading_assistant_api/common/types/response.go
@@ -3,4 +3,5 @@ package types
 type Response struct {
 	Status  bool   `json:"status"`
 	Message string `json:"message"`
+	Data interface{} `json:"data,omitempty"`
 }
diff --git a/trading_assistant_api/services/user/main.go b/trading_assistant_api/services/user/main.go
index e8e8ac7..39d39dd 100644
--- a/trading_assistant_api/services/user/main.go
+++ b/trading_assistant_api/services/user/main.go
@@ -67,12 +67,10 @@ func main() {
 func routes() http.Handler {
 	mux := http.NewServeMux()
 	mux.HandleFunc("/healthz", func(w http.ResponseWriter, r *http.Request) {
-		w.WriteHeader(http.StatusOK)
-		w.Write([]byte("ok"))
+		writeJSON(w, http.StatusOK, true, "ok", nil)
 	})
 	mux.HandleFunc("/version", func(w http.ResponseWriter, r *http.Request) {
-		w.WriteHeader(http.StatusOK)
-		w.Write([]byte("user-service v0.1.0"))
+		writeJSON(w, http.StatusOK, true, "ok", map[string]string{"version": "user-service v0.1.0"})
 	})
 	mux.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
 		fmt.Fprintf(w, "hello from user-service")
@@ -96,26 +94,26 @@ type loginResp struct {
 
 func registerHandler(w http.ResponseWriter, r *http.Request) {
 	if r.Method != http.MethodPost {
-		writeJSON(w, http.StatusMethodNotAllowed, false, "method not allowed")
+		writeJSON(w, http.StatusMethodNotAllowed, false, "method not allowed", nil)
 		return
 	}
 	var req registerReq
 	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
-		writeJSON(w, http.StatusBadRequest, false, "invalid json")
+		writeJSON(w, http.StatusBadRequest, false, "invalid json", nil)
 		return
 	}
 	if !validAccount(req.Account) || !validPassword(req.Password) {
-		writeJSON(w, http.StatusBadRequest, false, "invalid account or password")
+		writeJSON(w, http.StatusBadRequest, false, "invalid account or password", nil)
 		return
 	}
 	hashed, err := bcrypt.GenerateFromPassword([]byte(req.Password), 12)
 	if err != nil {
-		writeJSON(w, http.StatusInternalServerError, false, "internal error")
+		writeJSON(w, http.StatusInternalServerError, false, "internal error", nil)
 		return
 	}
 	tx, err := pg.Begin()
 	if err != nil {
-		writeJSON(w, http.StatusInternalServerError, false, "internal error")
+		writeJSON(w, http.StatusInternalServerError, false, "internal error", nil)
 		return
 	}
 	defer func() {
@@ -123,57 +121,57 @@ func registerHandler(w http.ResponseWriter, r *http.Request) {
 	}()
 	var userID string
 	if err := tx.QueryRow(`INSERT INTO users DEFAULT VALUES RETURNING user_id`).Scan(&userID); err != nil {
-		writeJSON(w, http.StatusInternalServerError, false, "internal error")
+		writeJSON(w, http.StatusInternalServerError, false, "internal error", nil)
 		return
 	}
 	if _, err := tx.Exec(`INSERT INTO user_login_accounts (user_id, value, deleted) VALUES ($1, $2, false)`, userID, req.Account); err != nil {
 		if isUniqueViolation(err) {
-			writeJSON(w, http.StatusConflict, false, "account exists")
+			writeJSON(w, http.StatusConflict, false, "account exists", nil)
 			return
 		}
-		writeJSON(w, http.StatusInternalServerError, false, "internal error")
+		writeJSON(w, http.StatusInternalServerError, false, "internal error", nil)
 		return
 	}
 	if _, err := tx.Exec(`INSERT INTO user_login_passwords (user_id, value, deleted) VALUES ($1, $2, false)`, userID, string(hashed)); err != nil {
-		writeJSON(w, http.StatusInternalServerError, false, "internal error")
+		writeJSON(w, http.StatusInternalServerError, false, "internal error", nil)
 		return
 	}
 	if err := tx.Commit(); err != nil {
-		writeJSON(w, http.StatusInternalServerError, false, "internal error")
+		writeJSON(w, http.StatusInternalServerError, false, "internal error", nil)
 		return
 	}
-	writeJSON(w, http.StatusCreated, true, userID)
+	writeJSON(w, http.StatusCreated, true, "ok", map[string]string{"user_id": userID})
 }
 
 func loginHandler(w http.ResponseWriter, r *http.Request) {
 	if r.Method != http.MethodPost {
-		writeJSON(w, http.StatusMethodNotAllowed, false, "method not allowed")
+		writeJSON(w, http.StatusMethodNotAllowed, false, "method not allowed", nil)
 		return
 	}
 	var req loginReq
 	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
-		writeJSON(w, http.StatusBadRequest, false, "invalid json")
+		writeJSON(w, http.StatusBadRequest, false, "invalid json", nil)
 		return
 	}
 	if !validAccount(req.Account) || !validPassword(req.Password) {
-		writeJSON(w, http.StatusBadRequest, false, "invalid account or password")
+		writeJSON(w, http.StatusBadRequest, false, "invalid account or password", nil)
 		return
 	}
 	var userID string
 	if err := pg.QueryRow(`SELECT user_id FROM user_login_accounts WHERE value = $1 AND deleted = false`, req.Account).Scan(&userID); err != nil {
-		writeJSON(w, http.StatusUnauthorized, false, "unauthorized")
+		writeJSON(w, http.StatusUnauthorized, false, "unauthorized", nil)
 		return
 	}
 	var hashed string
 	if err := pg.QueryRow(`SELECT value FROM user_login_passwords WHERE user_id = $1 AND deleted = false`, userID).Scan(&hashed); err != nil {
-		writeJSON(w, http.StatusUnauthorized, false, "unauthorized")
+		writeJSON(w, http.StatusUnauthorized, false, "unauthorized", nil)
 		return
 	}
 	if bcrypt.CompareHashAndPassword([]byte(hashed), []byte(req.Password)) != nil {
-		writeJSON(w, http.StatusUnauthorized, false, "unauthorized")
+		writeJSON(w, http.StatusUnauthorized, false, "unauthorized", nil)
 		return
 	}
-	writeJSON(w, http.StatusOK, true, userID)
+	writeJSON(w, http.StatusOK, true, "ok", map[string]string{"user_id": userID})
 }
 
 func validAccount(a string) bool {
@@ -205,8 +203,8 @@ func applySchema(path string) error {
 	return err
 }
 
-func writeJSON(w http.ResponseWriter, code int, status bool, msg string) {
+func writeJSON(w http.ResponseWriter, code int, status bool, msg string, data interface{}) {
 	w.Header().Set("Content-Type", "application/json")
 	w.WriteHeader(code)
-	json.NewEncoder(w).Encode(types.Response{Status: status, Message: msg})
+	json.NewEncoder(w).Encode(types.Response{Status: status, Message: msg, Data: data})
 }