diff --git a/auth-view/src/pages/LoginPage.tsx b/auth-view/src/pages/LoginPage.tsx
index dfd9ee6..d1c77ea 100644
--- a/auth-view/src/pages/LoginPage.tsx
+++ b/auth-view/src/pages/LoginPage.tsx
@@ -33,7 +33,7 @@ export default function LoginPage() {
       const res = await fetch("/api/auth/login", {
         method: "POST",
         headers: { "Content-Type": "application/json" },
-        body: JSON.stringify({ email, password }),
+        body: JSON.stringify({ email: email.toLowerCase(), password }),
       });
       const data = await res.json();
       if (data.success && data.payload?.token) {
diff --git a/auth-view/src/pages/RegisterPage.tsx b/auth-view/src/pages/RegisterPage.tsx
index d9c752c..00e4657 100644
--- a/auth-view/src/pages/RegisterPage.tsx
+++ b/auth-view/src/pages/RegisterPage.tsx
@@ -32,7 +32,7 @@ export default function RegisterPage() {
       const res = await fetch("/api/auth/register", {
         method: "POST",
         headers: { "Content-Type": "application/json" },
-        body: JSON.stringify({ username, email, password, confirmPassword }),
+        body: JSON.stringify({ username, email: email.toLowerCase(), password, confirmPassword }),
       });
       const data = await res.json();
       if (data.success && data.payload?.token) {
diff --git a/gateway-service/src/main/java/com/posthub/gateway/service/AuthService.java b/gateway-service/src/main/java/com/posthub/gateway/service/AuthService.java
index f8fa9c2..091ef8e 100644
--- a/gateway-service/src/main/java/com/posthub/gateway/service/AuthService.java
+++ b/gateway-service/src/main/java/com/posthub/gateway/service/AuthService.java
@@ -35,7 +35,7 @@ public class AuthService {
     private final PasswordEncoder passwordEncoder;
 
     public Mono<RagResponse<UserProfileDTO>> login(LoginRequest request) {
-        return userRepository.findByEmail(request.getEmail())
+        return userRepository.findByEmail(request.getEmail().toLowerCase())
                 .switchIfEmpty(Mono.error(new ResponseStatusException(
                         HttpStatus.UNAUTHORIZED, ApiErrorMessage.INVALID_USER_OR_PASSWORD.getMessage())))
                 .flatMap(user -> {
@@ -67,7 +67,7 @@ public class AuthService {
         return userRepository.findByUsername(request.getUsername())
                 .flatMap(existing -> Mono.<User>error(new ResponseStatusException(
                         HttpStatus.CONFLICT, ApiErrorMessage.USERNAME_ALREADY_EXISTS.getMessage(request.getUsername()))))
-                .switchIfEmpty(userRepository.existsByEmail(request.getEmail())
+                .switchIfEmpty(userRepository.existsByEmail(request.getEmail().toLowerCase())
                         .flatMap(exists -> {
                             if (exists) {
                                 return Mono.<User>error(new ResponseStatusException(
@@ -75,7 +75,7 @@ public class AuthService {
                             }
                             User user = new User();
                             user.setUsername(request.getUsername());
-                            user.setEmail(request.getEmail());
+                            user.setEmail(request.getEmail().toLowerCase());
                             user.setPassword(passwordEncoder.encode(request.getPassword()));
                             user.setRegistrationStatus(RegistrationStatus.ACTIVE);
                             user.setRole(UserRole.USER);