diff --git a/api/user_setting.go b/api/user_setting.go
index 5022e166..d540a560 100644
--- a/api/user_setting.go
+++ b/api/user_setting.go
@@ -1,5 +1,10 @@
 package api
 
+import (
+	"encoding/json"
+	"fmt"
+)
+
 type UserSettingKey string
 
 const (
@@ -20,6 +25,11 @@ func (key UserSettingKey) String() string {
 	return ""
 }
 
+var (
+	UserSettingLocaleValue         = []string{"en", "zh"}
+	UserSettingMemoVisibilityValue = []Visibility{Privite, Protected, Public}
+)
+
 type UserSetting struct {
 	UserID int
 	Key    UserSettingKey `json:"key"`
@@ -33,6 +43,48 @@ type UserSettingUpsert struct {
 	Value  string         `json:"value"`
 }
 
+func (upsert UserSettingUpsert) Validate() error {
+	if upsert.Key == UserSettingLocaleKey {
+		var localeValue string
+		err := json.Unmarshal([]byte(upsert.Value), &localeValue)
+		if err != nil {
+			return fmt.Errorf("failed to unmarshal user setting locale value")
+		}
+
+		invalid := true
+		for _, value := range UserSettingLocaleValue {
+			if localeValue == value {
+				invalid = false
+				break
+			}
+		}
+		if invalid {
+			return fmt.Errorf("invalid user setting locale value")
+		}
+	} else if upsert.Key == UserSettingMemoVisibilityKey {
+		var memoVisibilityValue Visibility
+		err := json.Unmarshal([]byte(upsert.Value), &memoVisibilityValue)
+		if err != nil {
+			return fmt.Errorf("failed to unmarshal user setting memo visibility value")
+		}
+
+		invalid := true
+		for _, value := range UserSettingMemoVisibilityValue {
+			if memoVisibilityValue == value {
+				invalid = false
+				break
+			}
+		}
+		if invalid {
+			return fmt.Errorf("invalid user setting memo visibility value")
+		}
+	} else {
+		return fmt.Errorf("invalid user setting key")
+	}
+
+	return nil
+}
+
 type UserSettingFind struct {
 	UserID int
 
diff --git a/server/memo.go b/server/memo.go
index 82582702..84b9747c 100644
--- a/server/memo.go
+++ b/server/memo.go
@@ -43,7 +43,10 @@ func (s *Server) registerMemoRoutes(g *echo.Group) {
 		}
 		if userMemoVisibilitySetting != nil {
 			memoVisibility := api.Privite
-			json.Unmarshal([]byte(userMemoVisibilitySetting.Value), &memoVisibility)
+			err := json.Unmarshal([]byte(userMemoVisibilitySetting.Value), &memoVisibility)
+			if err != nil {
+				return echo.NewHTTPError(http.StatusInternalServerError, "Failed to unmarshal user setting value").SetInternal(err)
+			}
 			memoCreate.Visibility = memoVisibility
 		}
 
diff --git a/server/user.go b/server/user.go
index 57102ce9..b9b14e3d 100644
--- a/server/user.go
+++ b/server/user.go
@@ -118,9 +118,8 @@ func (s *Server) registerUserRoutes(g *echo.Group) {
 		if err := json.NewDecoder(c.Request().Body).Decode(userSettingUpsert); err != nil {
 			return echo.NewHTTPError(http.StatusBadRequest, "Malformatted post user setting upsert request").SetInternal(err)
 		}
-
-		if userSettingUpsert.Key.String() == "" {
-			return echo.NewHTTPError(http.StatusBadRequest, "Invalid user setting key")
+		if err := userSettingUpsert.Validate(); err != nil {
+			return echo.NewHTTPError(http.StatusBadRequest, "Invalid user setting format").SetInternal(err)
 		}
 
 		userSettingUpsert.UserID = userID
@@ -191,6 +190,10 @@ func (s *Server) registerUserRoutes(g *echo.Group) {
 			return echo.NewHTTPError(http.StatusBadRequest, "Malformatted patch user request").SetInternal(err)
 		}
 
+		if userPatch.Email != nil && !common.ValidateEmail(*userPatch.Email) {
+			return echo.NewHTTPError(http.StatusBadRequest, "Invalid email format")
+		}
+
 		if userPatch.Password != nil && *userPatch.Password != "" {
 			passwordHash, err := bcrypt.GenerateFromPassword([]byte(*userPatch.Password), bcrypt.DefaultCost)
 			if err != nil {