diff --git a/backend/build.gradle b/backend/build.gradle
index 499d544..2d135e8 100644
--- a/backend/build.gradle
+++ b/backend/build.gradle
@@ -18,6 +18,7 @@ dependencies {
 	implementation 'org.springframework.boot:spring-boot-starter-actuator'
 
 	implementation 'org.springframework.boot:spring-boot-starter-data-jpa'
+	implementation 'org.springframework.boot:spring-boot-starter-data-rest'
 	compileOnly 'org.projectlombok:lombok'
 	annotationProcessor 'org.projectlombok:lombok'
 	implementation 'org.mariadb.jdbc:mariadb-java-client'
diff --git a/backend/src/main/java/de/hft/geotime/record/TimeRecord.java b/backend/src/main/java/de/hft/geotime/record/TimeRecord.java
index 6e7293a..c349c58 100644
--- a/backend/src/main/java/de/hft/geotime/record/TimeRecord.java
+++ b/backend/src/main/java/de/hft/geotime/record/TimeRecord.java
@@ -5,9 +5,7 @@ import lombok.AllArgsConstructor;
 import lombok.Data;
 import lombok.NoArgsConstructor;
 
-import javax.persistence.Entity;
-import javax.persistence.Id;
-import javax.persistence.OneToOne;
+import javax.persistence.*;
 import java.time.Duration;
 import java.util.Date;
 
@@ -18,6 +16,7 @@ import java.util.Date;
 public class TimeRecord {
 
     @Id
+    @GeneratedValue(strategy = GenerationType.IDENTITY)
     private long id;
     @OneToOne
     private TimetrackAccount account; // TimetrackAccount ID (Lazy)
diff --git a/backend/src/main/java/de/hft/geotime/role/Role.java b/backend/src/main/java/de/hft/geotime/role/Role.java
index 7b319b7..f887577 100644
--- a/backend/src/main/java/de/hft/geotime/role/Role.java
+++ b/backend/src/main/java/de/hft/geotime/role/Role.java
@@ -16,7 +16,7 @@ import javax.persistence.Id;
 public class Role {
 
     @Id
-    @GeneratedValue(strategy = GenerationType.AUTO)
+    @GeneratedValue(strategy = GenerationType.IDENTITY)
     private long id;
     private String name;
     // TODO: Permission List
diff --git a/backend/src/main/java/de/hft/geotime/security/SecurityConstants.java b/backend/src/main/java/de/hft/geotime/security/SecurityConstants.java
index d568748..f977cf3 100644
--- a/backend/src/main/java/de/hft/geotime/security/SecurityConstants.java
+++ b/backend/src/main/java/de/hft/geotime/security/SecurityConstants.java
@@ -5,5 +5,5 @@ public class SecurityConstants {
     public static final long EXPIRATION_TIME = 864_000_000; // 10 days
     public static final String TOKEN_PREFIX = "Bearer ";
     public static final String HEADER_STRING = "Authorization";
-    public static final String SIGN_UP_URL = "/user/sign-up";
+    public static final String SIGN_UP_URL = "/sign-up";
 }
\ No newline at end of file
diff --git a/backend/src/main/java/de/hft/geotime/timetrackaccount/TimetrackAccount.java b/backend/src/main/java/de/hft/geotime/timetrackaccount/TimetrackAccount.java
index 4d0c8e1..7a220f1 100644
--- a/backend/src/main/java/de/hft/geotime/timetrackaccount/TimetrackAccount.java
+++ b/backend/src/main/java/de/hft/geotime/timetrackaccount/TimetrackAccount.java
@@ -14,7 +14,7 @@ import javax.persistence.*;
 public class TimetrackAccount {
 
     @Id
-    @GeneratedValue(strategy = GenerationType.AUTO)
+    @GeneratedValue(strategy = GenerationType.IDENTITY)
     private long id;
     @OneToOne
     private TimetrackUser timetrackUser; // TimetrackUser Id (Lazy) [REMOVE]
diff --git a/backend/src/main/java/de/hft/geotime/user/TimetrackUser.java b/backend/src/main/java/de/hft/geotime/user/TimetrackUser.java
index 47f85df..8dcc7c7 100644
--- a/backend/src/main/java/de/hft/geotime/user/TimetrackUser.java
+++ b/backend/src/main/java/de/hft/geotime/user/TimetrackUser.java
@@ -5,7 +5,6 @@ import de.hft.geotime.timetrackaccount.TimetrackAccount;
 import lombok.AllArgsConstructor;
 import lombok.Data;
 import lombok.NoArgsConstructor;
-import org.hibernate.validator.constraints.UniqueElements;
 
 import javax.persistence.*;
 import java.util.List;
@@ -17,9 +16,9 @@ import java.util.List;
 public class TimetrackUser {
 
     @Id
-    @GeneratedValue(strategy = GenerationType.AUTO)
+    @GeneratedValue(strategy = GenerationType.IDENTITY)
     private long id;
-    @UniqueElements
+    @Column(unique = true)
     private String username;
     private String password;        // strip
     private String firstname;
diff --git a/backend/src/main/java/de/hft/geotime/user/UserController.java b/backend/src/main/java/de/hft/geotime/user/UserController.java
index 5d73f85..723dde1 100644
--- a/backend/src/main/java/de/hft/geotime/user/UserController.java
+++ b/backend/src/main/java/de/hft/geotime/user/UserController.java
@@ -1,35 +1,38 @@
 package de.hft.geotime.user;
 
+import org.springframework.http.HttpStatus;
+import org.springframework.http.ResponseEntity;
 import org.springframework.security.core.Authentication;
 import org.springframework.security.crypto.bcrypt.BCryptPasswordEncoder;
 import org.springframework.web.bind.annotation.*;
 
-import java.util.HashMap;
-
 @RestController
-@RequestMapping("/user")
 public class UserController {
 
-    private TimetrackUserRepository userRepository;
-    private BCryptPasswordEncoder bCryptPasswordEncoder;
+    private final TimetrackUserRepository userRepository;
+    private final BCryptPasswordEncoder bCryptPasswordEncoder;
 
     public UserController(TimetrackUserRepository userRepository, BCryptPasswordEncoder bCryptPasswordEncoder) {
         this.userRepository = userRepository;
         this.bCryptPasswordEncoder = bCryptPasswordEncoder;
     }
 
-    @GetMapping
+    @GetMapping("/whoami")
     public String getUsername(Authentication authentication) {
         TimetrackUser timetrackUser = userRepository.findFirstByUsername(authentication.getName());
         return "Welcome back " + timetrackUser.getFirstname() + " " + timetrackUser.getLastname();
     }
 
-    // TODO: implement register, maybe move to another class
     @PostMapping("/sign-up")
-    public HashMap<String, Object> signUp(@RequestBody HashMap<String, Object> payload) {
-        return payload;
-        // user.setPassword(bCryptPasswordEncoder.encode(user.getPassword()));
-        // userRepository.save(user);
+    public ResponseEntity<String> signUp(@RequestBody TimetrackUser user) {
+        user.setPassword(bCryptPasswordEncoder.encode(user.getPassword()));
+        TimetrackUser byUsername = userRepository.findFirstByUsername(user.getUsername());
+        if (byUsername == null) {
+            userRepository.save(user);
+            return new ResponseEntity<>("Created", HttpStatus.CREATED);
+        } else {
+            return new ResponseEntity<>("Username already exists!", HttpStatus.CONFLICT);
+        }
     }
 
 }