diff --git a/api/v1/activity.go b/api/v1/activity.go
index dfb1898..3e1112d 100644
--- a/api/v1/activity.go
+++ b/api/v1/activity.go
@@ -1,11 +1,11 @@
 package v1
 
 type ActivityShorcutCreatePayload struct {
-	ShortcutID int `json:"shortcutId"`
+	ShortcutID int32 `json:"shortcutId"`
 }
 
 type ActivityShorcutViewPayload struct {
-	ShortcutID int    `json:"shortcutId"`
+	ShortcutID int32  `json:"shortcutId"`
 	IP         string `json:"ip"`
 	Referer    string `json:"referer"`
 	UserAgent  string `json:"userAgent"`
diff --git a/api/v1/jwt.go b/api/v1/jwt.go
index 64c0daf..1e8a7ac 100644
--- a/api/v1/jwt.go
+++ b/api/v1/jwt.go
@@ -3,7 +3,6 @@ package v1
 import (
 	"fmt"
 	"net/http"
-	"strconv"
 	"strings"
 	"time"
 
@@ -27,7 +26,7 @@ type claimsMessage struct {
 }
 
 // GenerateAccessToken generates an access token for web.
-func GenerateAccessToken(username string, userID int, secret string) (string, error) {
+func GenerateAccessToken(username string, userID int32, secret string) (string, error) {
 	expirationTime := time.Now().Add(auth.AccessTokenDuration)
 	return generateToken(username, userID, auth.AccessTokenAudienceName, expirationTime, []byte(secret))
 }
@@ -64,7 +63,7 @@ func setTokenCookie(c echo.Context, name, token string, expiration time.Time) {
 }
 
 // generateToken generates a jwt token.
-func generateToken(username string, userID int, aud string, expirationTime time.Time, secret []byte) (string, error) {
+func generateToken(username string, userID int32, aud string, expirationTime time.Time, secret []byte) (string, error) {
 	// Create the JWT claims, which includes the username and expiry time.
 	claims := &claimsMessage{
 		Name: username,
@@ -74,7 +73,7 @@ func generateToken(username string, userID int, aud string, expirationTime time.
 			ExpiresAt: jwt.NewNumericDate(expirationTime),
 			IssuedAt:  jwt.NewNumericDate(time.Now()),
 			Issuer:    auth.Issuer,
-			Subject:   strconv.Itoa(userID),
+			Subject:   fmt.Sprint(userID),
 		},
 	}
 
@@ -172,9 +171,9 @@ func JWTMiddleware(server *APIV1Service, next echo.HandlerFunc, secret string) e
 		}
 
 		// We either have a valid access token or we will attempt to generate new access token and refresh token
-		userID, err := strconv.Atoi(claims.Subject)
+		userID, err := util.ConvertStringToInt32(claims.Subject)
 		if err != nil {
-			return echo.NewHTTPError(http.StatusUnauthorized, "Malformed ID in the token.")
+			return echo.NewHTTPError(http.StatusUnauthorized, "Malformed ID in the token.").WithInternal(err)
 		}
 
 		// Even if there is no error, we still need to make sure the user still exists.
diff --git a/api/v1/redirector.go b/api/v1/redirector.go
index fcfb435..f75bf59 100644
--- a/api/v1/redirector.go
+++ b/api/v1/redirector.go
@@ -31,7 +31,7 @@ func (s *APIV1Service) registerRedirectorRoutes(g *echo.Group) {
 			return echo.NewHTTPError(http.StatusNotFound, fmt.Sprintf("not found shortcut with name: %s", shortcutName))
 		}
 		if shortcut.Visibility != store.VisibilityPublic {
-			userID, ok := c.Get(UserIDContextKey).(int)
+			userID, ok := c.Get(UserIDContextKey).(int32)
 			if !ok {
 				return echo.NewHTTPError(http.StatusUnauthorized, "Unauthorized")
 			}
diff --git a/api/v1/shortcut.go b/api/v1/shortcut.go
index 5a66492..7267e11 100644
--- a/api/v1/shortcut.go
+++ b/api/v1/shortcut.go
@@ -5,9 +5,9 @@ import (
 	"encoding/json"
 	"fmt"
 	"net/http"
-	"strconv"
 	"strings"
 
+	"github.com/boojack/slash/internal/util"
 	"github.com/boojack/slash/store"
 	"github.com/labstack/echo/v4"
 	"github.com/pkg/errors"
@@ -36,10 +36,10 @@ type OpenGraphMetadata struct {
 }
 
 type Shortcut struct {
-	ID int `json:"id"`
+	ID int32 `json:"id"`
 
 	// Standard fields
-	CreatorID int       `json:"creatorId"`
+	CreatorID int32     `json:"creatorId"`
 	Creator   *User     `json:"creator"`
 	CreatedTs int64     `json:"createdTs"`
 	UpdatedTs int64     `json:"updatedTs"`
@@ -80,7 +80,7 @@ type PatchShortcutRequest struct {
 func (s *APIV1Service) registerShortcutRoutes(g *echo.Group) {
 	g.POST("/shortcut", func(c echo.Context) error {
 		ctx := c.Request().Context()
-		userID, ok := c.Get(UserIDContextKey).(int)
+		userID, ok := c.Get(UserIDContextKey).(int32)
 		if !ok {
 			return echo.NewHTTPError(http.StatusUnauthorized, "missing user in session")
 		}
@@ -120,11 +120,11 @@ func (s *APIV1Service) registerShortcutRoutes(g *echo.Group) {
 
 	g.PATCH("/shortcut/:shortcutId", func(c echo.Context) error {
 		ctx := c.Request().Context()
-		shortcutID, err := strconv.Atoi(c.Param("shortcutId"))
+		shortcutID, err := util.ConvertStringToInt32(c.Param("shortcutId"))
 		if err != nil {
 			return echo.NewHTTPError(http.StatusBadRequest, fmt.Sprintf("shortcut ID is not a number: %s", c.Param("shortcutId"))).SetInternal(err)
 		}
-		userID, ok := c.Get(UserIDContextKey).(int)
+		userID, ok := c.Get(UserIDContextKey).(int32)
 		if !ok {
 			return echo.NewHTTPError(http.StatusUnauthorized, "missing user in session")
 		}
@@ -195,7 +195,7 @@ func (s *APIV1Service) registerShortcutRoutes(g *echo.Group) {
 
 	g.GET("/shortcut", func(c echo.Context) error {
 		ctx := c.Request().Context()
-		userID, ok := c.Get(UserIDContextKey).(int)
+		userID, ok := c.Get(UserIDContextKey).(int32)
 		if !ok {
 			return echo.NewHTTPError(http.StatusUnauthorized, "missing user in session")
 		}
@@ -234,7 +234,7 @@ func (s *APIV1Service) registerShortcutRoutes(g *echo.Group) {
 
 	g.GET("/shortcut/:id", func(c echo.Context) error {
 		ctx := c.Request().Context()
-		shortcutID, err := strconv.Atoi(c.Param("id"))
+		shortcutID, err := util.ConvertStringToInt32(c.Param("id"))
 		if err != nil {
 			return echo.NewHTTPError(http.StatusBadRequest, fmt.Sprintf("shortcut id is not a number: %s", c.Param("id"))).SetInternal(err)
 		}
@@ -258,11 +258,11 @@ func (s *APIV1Service) registerShortcutRoutes(g *echo.Group) {
 
 	g.DELETE("/shortcut/:id", func(c echo.Context) error {
 		ctx := c.Request().Context()
-		shortcutID, err := strconv.Atoi(c.Param("id"))
+		shortcutID, err := util.ConvertStringToInt32(c.Param("id"))
 		if err != nil {
 			return echo.NewHTTPError(http.StatusBadRequest, fmt.Sprintf("shortcut id is not a number: %s", c.Param("id"))).SetInternal(err)
 		}
-		userID, ok := c.Get(UserIDContextKey).(int)
+		userID, ok := c.Get(UserIDContextKey).(int32)
 		if !ok {
 			return echo.NewHTTPError(http.StatusUnauthorized, "missing user in session")
 		}
diff --git a/api/v1/user.go b/api/v1/user.go
index 67d1f2c..a0ae3b8 100644
--- a/api/v1/user.go
+++ b/api/v1/user.go
@@ -5,8 +5,8 @@ import (
 	"fmt"
 	"net/http"
 	"net/mail"
-	"strconv"
 
+	"github.com/boojack/slash/internal/util"
 	"github.com/boojack/slash/store"
 	"github.com/labstack/echo/v4"
 	"golang.org/x/crypto/bcrypt"
@@ -38,7 +38,7 @@ func (r Role) String() string {
 }
 
 type User struct {
-	ID int `json:"id"`
+	ID int32 `json:"id"`
 
 	// Standard fields
 	CreatedTs int64     `json:"createdTs"`
@@ -83,7 +83,7 @@ type PatchUserRequest struct {
 func (s *APIV1Service) registerUserRoutes(g *echo.Group) {
 	g.POST("/user", func(c echo.Context) error {
 		ctx := c.Request().Context()
-		userID, ok := c.Get(UserIDContextKey).(int)
+		userID, ok := c.Get(UserIDContextKey).(int32)
 		if !ok {
 			return echo.NewHTTPError(http.StatusUnauthorized, "Missing auth session")
 		}
@@ -144,7 +144,7 @@ func (s *APIV1Service) registerUserRoutes(g *echo.Group) {
 	// GET /api/user/me is used to check if the user is logged in.
 	g.GET("/user/me", func(c echo.Context) error {
 		ctx := c.Request().Context()
-		userID, ok := c.Get(UserIDContextKey).(int)
+		userID, ok := c.Get(UserIDContextKey).(int32)
 		if !ok {
 			return echo.NewHTTPError(http.StatusUnauthorized, "missing auth session")
 		}
@@ -161,7 +161,7 @@ func (s *APIV1Service) registerUserRoutes(g *echo.Group) {
 
 	g.GET("/user/:id", func(c echo.Context) error {
 		ctx := c.Request().Context()
-		userID, err := strconv.Atoi(c.Param("id"))
+		userID, err := util.ConvertStringToInt32(c.Param("id"))
 		if err != nil {
 			return echo.NewHTTPError(http.StatusBadRequest, fmt.Sprintf("user id is not a number: %s", c.Param("id"))).SetInternal(err)
 		}
@@ -178,11 +178,11 @@ func (s *APIV1Service) registerUserRoutes(g *echo.Group) {
 
 	g.PATCH("/user/:id", func(c echo.Context) error {
 		ctx := c.Request().Context()
-		userID, err := strconv.Atoi(c.Param("id"))
+		userID, err := util.ConvertStringToInt32(c.Param("id"))
 		if err != nil {
 			return echo.NewHTTPError(http.StatusBadRequest, fmt.Sprintf("user id is not a number: %s", c.Param("id"))).SetInternal(err)
 		}
-		currentUserID, ok := c.Get(UserIDContextKey).(int)
+		currentUserID, ok := c.Get(UserIDContextKey).(int32)
 		if !ok {
 			return echo.NewHTTPError(http.StatusUnauthorized, "missing user in session")
 		}
@@ -254,7 +254,7 @@ func (s *APIV1Service) registerUserRoutes(g *echo.Group) {
 
 	g.DELETE("/user/:id", func(c echo.Context) error {
 		ctx := c.Request().Context()
-		currentUserID, ok := c.Get(UserIDContextKey).(int)
+		currentUserID, ok := c.Get(UserIDContextKey).(int32)
 		if !ok {
 			return echo.NewHTTPError(http.StatusUnauthorized, "missing user in session")
 		}
@@ -271,7 +271,7 @@ func (s *APIV1Service) registerUserRoutes(g *echo.Group) {
 			return echo.NewHTTPError(http.StatusForbidden, "access forbidden for current session user").SetInternal(err)
 		}
 
-		userID, err := strconv.Atoi(c.Param("id"))
+		userID, err := util.ConvertStringToInt32(c.Param("id"))
 		if err != nil {
 			return echo.NewHTTPError(http.StatusBadRequest, fmt.Sprintf("user id is not a number: %s", c.Param("id"))).SetInternal(err)
 		}
diff --git a/api/v1/workspace.go b/api/v1/workspace.go
index 815211c..b18cc59 100644
--- a/api/v1/workspace.go
+++ b/api/v1/workspace.go
@@ -62,7 +62,7 @@ func (s *APIV1Service) registerWorkspaceRoutes(g *echo.Group) {
 
 	g.POST("/workspace/setting", func(c echo.Context) error {
 		ctx := c.Request().Context()
-		userID, ok := c.Get(UserIDContextKey).(int)
+		userID, ok := c.Get(UserIDContextKey).(int32)
 		if !ok {
 			return echo.NewHTTPError(http.StatusUnauthorized, "missing user in session")
 		}
@@ -97,7 +97,7 @@ func (s *APIV1Service) registerWorkspaceRoutes(g *echo.Group) {
 
 	g.GET("/workspace/setting", func(c echo.Context) error {
 		ctx := c.Request().Context()
-		userID, ok := c.Get(UserIDContextKey).(int)
+		userID, ok := c.Get(UserIDContextKey).(int32)
 		if !ok {
 			return echo.NewHTTPError(http.StatusUnauthorized, "missing user in session")
 		}
diff --git a/api/v2/jwt.go b/api/v2/jwt.go
index 7399f36..b05216c 100644
--- a/api/v2/jwt.go
+++ b/api/v2/jwt.go
@@ -8,6 +8,7 @@ import (
 	"time"
 
 	"github.com/boojack/slash/api/auth"
+	"github.com/boojack/slash/internal/util"
 	"github.com/boojack/slash/store"
 	"github.com/golang-jwt/jwt/v4"
 	"github.com/pkg/errors"
@@ -76,7 +77,7 @@ func (in *GRPCAuthInterceptor) AuthenticationInterceptor(ctx context.Context, re
 	return handler(childCtx, request)
 }
 
-func (in *GRPCAuthInterceptor) authenticate(ctx context.Context, accessTokenStr string) (int, error) {
+func (in *GRPCAuthInterceptor) authenticate(ctx context.Context, accessTokenStr string) (int32, error) {
 	if accessTokenStr == "" {
 		return 0, status.Errorf(codes.Unauthenticated, "access token not found")
 	}
@@ -103,7 +104,7 @@ func (in *GRPCAuthInterceptor) authenticate(ctx context.Context, accessTokenStr
 		)
 	}
 
-	userID, err := strconv.Atoi(claims.Subject)
+	userID, err := util.ConvertStringToInt32(claims.Subject)
 	if err != nil {
 		return 0, status.Errorf(codes.Unauthenticated, "malformed ID %q in the access token", claims.Subject)
 	}
diff --git a/api/v2/user_service.go b/api/v2/user_service.go
index 661f016..7e4985a 100644
--- a/api/v2/user_service.go
+++ b/api/v2/user_service.go
@@ -23,9 +23,8 @@ func NewUserService(store *store.Store) *UserService {
 }
 
 func (s *UserService) GetUser(ctx context.Context, request *apiv2pb.GetUserRequest) (*apiv2pb.GetUserResponse, error) {
-	id := int(request.Id)
 	user, err := s.Store.GetUser(ctx, &store.FindUser{
-		ID: &id,
+		ID: &request.Id,
 	})
 	if err != nil {
 		return nil, status.Errorf(codes.Internal, "failed to list tags: %v", err)
diff --git a/internal/util/util.go b/internal/util/util.go
index 1547b05..4b0fb10 100644
--- a/internal/util/util.go
+++ b/internal/util/util.go
@@ -1,6 +1,18 @@
 package util
 
-import "strings"
+import (
+	"strconv"
+	"strings"
+)
+
+// ConvertStringToInt32 converts a string to int32.
+func ConvertStringToInt32(src string) (int32, error) {
+	i, err := strconv.Atoi(src)
+	if err != nil {
+		return 0, err
+	}
+	return int32(i), nil
+}
 
 // HasPrefixes returns true if the string s has any of the given prefixes.
 func HasPrefixes(src string, prefixes ...string) bool {
diff --git a/store/activity.go b/store/activity.go
index c9af102..eee14be 100644
--- a/store/activity.go
+++ b/store/activity.go
@@ -48,8 +48,8 @@ func (l ActivityLevel) String() string {
 }
 
 type Activity struct {
-	ID        int
-	CreatorID int
+	ID        int32
+	CreatorID int32
 	CreatedTs int64
 	Type      ActivityType
 	Level     ActivityLevel
diff --git a/store/cache.go b/store/cache.go
index 0678692..e946eda 100644
--- a/store/cache.go
+++ b/store/cache.go
@@ -2,6 +2,6 @@ package store
 
 import "fmt"
 
-func getUserSettingCacheKey(userID int, key string) string {
+func getUserSettingCacheKey(userID int32, key string) string {
 	return fmt.Sprintf("%d-%s", userID, key)
 }
diff --git a/store/shortcut.go b/store/shortcut.go
index e4f514b..76a7415 100644
--- a/store/shortcut.go
+++ b/store/shortcut.go
@@ -39,10 +39,10 @@ type OpenGraphMetadata struct {
 }
 
 type Shortcut struct {
-	ID int
+	ID int32
 
 	// Standard fields
-	CreatorID int
+	CreatorID int32
 	CreatedTs int64
 	UpdatedTs int64
 	RowStatus RowStatus
@@ -58,7 +58,7 @@ type Shortcut struct {
 }
 
 type UpdateShortcut struct {
-	ID int
+	ID int32
 
 	RowStatus         *RowStatus
 	Name              *string
@@ -71,8 +71,8 @@ type UpdateShortcut struct {
 }
 
 type FindShortcut struct {
-	ID             *int
-	CreatorID      *int
+	ID             *int32
+	CreatorID      *int32
 	RowStatus      *RowStatus
 	Name           *string
 	VisibilityList []Visibility
@@ -80,7 +80,7 @@ type FindShortcut struct {
 }
 
 type DeleteShortcut struct {
-	ID int
+	ID int32
 }
 
 func (s *Store) CreateShortcut(ctx context.Context, create *Shortcut) (*Shortcut, error) {
diff --git a/store/user.go b/store/user.go
index 02c0f65..d1dcf75 100644
--- a/store/user.go
+++ b/store/user.go
@@ -17,7 +17,7 @@ const (
 )
 
 type User struct {
-	ID int
+	ID int32
 
 	// Standard fields
 	CreatedTs int64
@@ -32,7 +32,7 @@ type User struct {
 }
 
 type UpdateUser struct {
-	ID int
+	ID int32
 
 	RowStatus    *RowStatus
 	Email        *string
@@ -42,7 +42,7 @@ type UpdateUser struct {
 }
 
 type FindUser struct {
-	ID        *int
+	ID        *int32
 	RowStatus *RowStatus
 	Email     *string
 	Nickname  *string
@@ -50,7 +50,7 @@ type FindUser struct {
 }
 
 type DeleteUser struct {
-	ID int
+	ID int32
 }
 
 func (s *Store) CreateUser(ctx context.Context, create *User) (*User, error) {
diff --git a/store/user_setting.go b/store/user_setting.go
index 2324042..4d1e72d 100644
--- a/store/user_setting.go
+++ b/store/user_setting.go
@@ -7,13 +7,13 @@ import (
 )
 
 type UserSetting struct {
-	UserID int
+	UserID int32
 	Key    string
 	Value  string
 }
 
 type FindUserSetting struct {
-	UserID *int
+	UserID *int32
 	Key    string
 }