diff --git a/src/main/java/com/faf223/expensetrackerfaf/controller/ExpenseController.java b/src/main/java/com/faf223/expensetrackerfaf/controller/ExpenseController.java
index aed21b6..d2298e5 100644
--- a/src/main/java/com/faf223/expensetrackerfaf/controller/ExpenseController.java
+++ b/src/main/java/com/faf223/expensetrackerfaf/controller/ExpenseController.java
@@ -1,5 +1,8 @@
 package com.faf223.expensetrackerfaf.controller;
 
+import com.faf223.expensetrackerfaf.dto.ExpenseCreationDTO;
+import com.faf223.expensetrackerfaf.dto.ExpenseDTO;
+import com.faf223.expensetrackerfaf.dto.mappers.ExpenseMapper;
 import com.faf223.expensetrackerfaf.model.Expense;
 import com.faf223.expensetrackerfaf.service.ExpenseService;
 import org.springframework.beans.factory.annotation.Autowired;
@@ -8,50 +11,55 @@ import org.springframework.validation.BindingResult;
 import org.springframework.web.bind.annotation.*;
 
 import java.util.List;
+import java.util.stream.Collectors;
 
 @RestController
 @RequestMapping("/expenses")
 public class ExpenseController {
 
     private final ExpenseService expenseService;
+    private final ExpenseMapper expenseMapper;
 
     @Autowired
-    public ExpenseController(ExpenseService expenseService) {
+    public ExpenseController(ExpenseService expenseService, ExpenseMapper expenseMapper) {
         this.expenseService = expenseService;
+        this.expenseMapper = expenseMapper;
     }
 
     @GetMapping()
-    public ResponseEntity<List<Expense>> getAllExpenses() {
-        List<Expense> expenses = expenseService.getExpenses();
+    public ResponseEntity<List<ExpenseDTO>> getAllExpenses() {
+        List<ExpenseDTO> expenses = expenseService.getExpenses().stream().map(expenseMapper::toDto).collect(Collectors.toList());
         if (!expenses.isEmpty()) return ResponseEntity.ok(expenses);
         else return ResponseEntity.notFound().build();
     }
 
     @PostMapping()
-    public ResponseEntity<Expense> createNewExpense(@RequestBody Expense expense,
+    public ResponseEntity<ExpenseDTO> createNewExpense(@RequestBody ExpenseCreationDTO expenseDTO,
                          BindingResult bindingResult) {
+        Expense expense = expenseMapper.toExpense(expenseDTO);
         if (!bindingResult.hasErrors()) {
             expenseService.createOrUpdateExpense(expense);
-            return ResponseEntity.ok(expense);
+            return ResponseEntity.ok(expenseMapper.toDto(expense));
         } else {
             return ResponseEntity.notFound().build();
         }
     }
 
     @PatchMapping()
-    public ResponseEntity<Expense> updateExpense(@RequestBody Expense expense,
+    public ResponseEntity<ExpenseDTO> updateExpense(@RequestBody ExpenseCreationDTO expenseDTO,
                                                  BindingResult bindingResult) {
+        Expense expense = expenseMapper.toExpense(expenseDTO);
         if (!bindingResult.hasErrors()) {
             expenseService.createOrUpdateExpense(expense);
-            return ResponseEntity.ok(expense);
+            return ResponseEntity.ok(expenseMapper.toDto(expense));
         } else {
             return ResponseEntity.notFound().build();
         }
     }
 
     @GetMapping("/{userUuid}")
-    public ResponseEntity<List<Expense>> getExpensesByUser(@PathVariable String userUuid) {
-        List<Expense> expenses = expenseService.getExpensesByUserId(userUuid);
+    public ResponseEntity<List<ExpenseDTO>> getExpensesByUser(@PathVariable String userUuid) {
+        List<ExpenseDTO> expenses = expenseService.getExpensesByUserId(userUuid).stream().map(expenseMapper::toDto).collect(Collectors.toList());
         if (!expenses.isEmpty()) return ResponseEntity.ok(expenses);
         else return ResponseEntity.notFound().build();
     }
diff --git a/src/main/java/com/faf223/expensetrackerfaf/controller/IncomeController.java b/src/main/java/com/faf223/expensetrackerfaf/controller/IncomeController.java
index ffc0497..ad342f7 100644
--- a/src/main/java/com/faf223/expensetrackerfaf/controller/IncomeController.java
+++ b/src/main/java/com/faf223/expensetrackerfaf/controller/IncomeController.java
@@ -1,5 +1,8 @@
 package com.faf223.expensetrackerfaf.controller;
 
+import com.faf223.expensetrackerfaf.dto.IncomeCreationDTO;
+import com.faf223.expensetrackerfaf.dto.IncomeDTO;
+import com.faf223.expensetrackerfaf.dto.mappers.IncomeMapper;
 import com.faf223.expensetrackerfaf.model.Income;
 import com.faf223.expensetrackerfaf.service.IncomeService;
 import org.springframework.beans.factory.annotation.Autowired;
@@ -8,51 +11,55 @@ import org.springframework.validation.BindingResult;
 import org.springframework.web.bind.annotation.*;
 
 import java.util.List;
+import java.util.stream.Collectors;
 
 @RestController
 @RequestMapping("/incomes")
 public class IncomeController {
 
     private final IncomeService incomeService;
+    private final IncomeMapper incomeMapper;
 
     @Autowired
-    public IncomeController(IncomeService incomeService) {
+    public IncomeController(IncomeService incomeService, IncomeMapper incomeMapper) {
         this.incomeService = incomeService;
+        this.incomeMapper = incomeMapper;
     }
 
     @GetMapping()
-    public ResponseEntity<List<Income>> getAllIncomes() {
-        List<Income> incomes = incomeService.getIncomes();
+    public ResponseEntity<List<IncomeDTO>> getAllIncomes() {
+        List<IncomeDTO> incomes = incomeService.getIncomes().stream().map(incomeMapper::toDto).collect(Collectors.toList());
         if (!incomes.isEmpty()) return ResponseEntity.ok(incomes);
         else return ResponseEntity.notFound().build();
     }
 
     @PostMapping()
-    public ResponseEntity<Income> createNewIncome(@RequestBody Income income,
+    public ResponseEntity<IncomeDTO> createNewIncome(@RequestBody IncomeCreationDTO incomeDTO,
                                                     BindingResult bindingResult) {
+        Income income = incomeMapper.toIncome(incomeDTO);
         if (!bindingResult.hasErrors()) {
             incomeService.createOrUpdateIncome(income);
-            return ResponseEntity.ok(income);
+            return ResponseEntity.ok(incomeMapper.toDto(income));
         } else {
             return ResponseEntity.notFound().build();
         }
     }
 
     @PatchMapping()
-    public ResponseEntity<Income> updateIncome(@RequestBody Income income,
+    public ResponseEntity<IncomeDTO> updateIncome(@RequestBody IncomeCreationDTO incomeDTO,
                                                  BindingResult bindingResult) {
+        Income income = incomeMapper.toIncome(incomeDTO);
         if (!bindingResult.hasErrors()) {
-            System.out.println("amount: " + income.getAmount());
             incomeService.createOrUpdateIncome(income);
-            return ResponseEntity.ok(income);
+            return ResponseEntity.ok(incomeMapper.toDto(income));
         } else {
             return ResponseEntity.notFound().build();
         }
     }
 
     @GetMapping("/{userUuid}")
-    public ResponseEntity<List<Income>> getIncomesByUser(@PathVariable String userUuid) {
-        List<Income> incomes = incomeService.getIncomesByUserId(userUuid);
+    public ResponseEntity<List<IncomeDTO>> getIncomesByUser(@PathVariable String userUuid) {
+        List<IncomeDTO> incomes = incomeService.getIncomesByUserId(userUuid).stream().map(incomeMapper::toDto).collect(Collectors.toList());
         if (!incomes.isEmpty()) return ResponseEntity.ok(incomes);
         else return ResponseEntity.notFound().build();
     }
diff --git a/src/main/java/com/faf223/expensetrackerfaf/controller/UserController.java b/src/main/java/com/faf223/expensetrackerfaf/controller/UserController.java
index afe8623..97b3648 100644
--- a/src/main/java/com/faf223/expensetrackerfaf/controller/UserController.java
+++ b/src/main/java/com/faf223/expensetrackerfaf/controller/UserController.java
@@ -1,5 +1,8 @@
 package com.faf223.expensetrackerfaf.controller;
 
+import com.faf223.expensetrackerfaf.dto.UserCreationDTO;
+import com.faf223.expensetrackerfaf.dto.UserDTO;
+import com.faf223.expensetrackerfaf.dto.mappers.UserMapper;
 import com.faf223.expensetrackerfaf.model.User;
 import com.faf223.expensetrackerfaf.service.UserService;
 import org.springframework.beans.factory.annotation.Autowired;
@@ -8,51 +11,56 @@ import org.springframework.validation.BindingResult;
 import org.springframework.web.bind.annotation.*;
 
 import java.util.List;
+import java.util.stream.Collectors;
 
 @RestController
 @RequestMapping("/users")
 public class UserController {
 
     private final UserService userService;
+    private final UserMapper userMapper;
 
     @Autowired
-    public UserController(UserService userService) {
+    public UserController(UserService userService, UserMapper userMapper) {
         this.userService = userService;
+        this.userMapper = userMapper;
     }
 
     @GetMapping()
-    public ResponseEntity<List<User>> getAllUsers() {
-        List<User> users = userService.getUsers();
+    public ResponseEntity<List<UserDTO>> getAllUsers() {
+        List<UserDTO> users = userService.getUsers().stream().map(userMapper::toDto).collect(Collectors.toList());
         if (!users.isEmpty()) return ResponseEntity.ok(users);
         else return ResponseEntity.notFound().build();
     }
 
     @PostMapping()
-    public ResponseEntity<User> createNewUser(@RequestBody User user,
+    public ResponseEntity<UserDTO> createNewUser(@RequestBody UserCreationDTO userDTO,
                                                   BindingResult bindingResult) {
+        User user = userMapper.toUser(userDTO);
         if (!bindingResult.hasErrors()) {
             userService.createOrUpdateUser(user);
-            return ResponseEntity.ok(user);
+            return ResponseEntity.ok(userMapper.toDto(user));
         } else {
             return ResponseEntity.notFound().build();
         }
     }
 
     @PatchMapping()
-    public ResponseEntity<User> updateUser(@RequestBody User user,
+    public ResponseEntity<UserDTO> updateUser(@RequestBody UserCreationDTO userDTO,
                                                BindingResult bindingResult) {
+        User user = userMapper.toUser(userDTO);
         if (!bindingResult.hasErrors()) {
             userService.createOrUpdateUser(user);
-            return ResponseEntity.ok(user);
+            return ResponseEntity.ok(userMapper.toDto(user));
         } else {
             return ResponseEntity.notFound().build();
         }
     }
 
     @GetMapping("/{userUuid}")
-    public ResponseEntity<User> getUser(@PathVariable String userUuid) {
+    public ResponseEntity<UserDTO> getUser(@PathVariable String userUuid) {
         User user = userService.getUserById(userUuid);
-        if (user != null) return ResponseEntity.ok(user);
+        if (user != null) return ResponseEntity.ok(userMapper.toDto(user));
         else return ResponseEntity.notFound().build();
     }
 }
diff --git a/src/main/java/com/faf223/expensetrackerfaf/dto/ExpenseCreationDTO.java b/src/main/java/com/faf223/expensetrackerfaf/dto/ExpenseCreationDTO.java
new file mode 100644
index 0000000..3042800
--- /dev/null
+++ b/src/main/java/com/faf223/expensetrackerfaf/dto/ExpenseCreationDTO.java
@@ -0,0 +1,12 @@
+package com.faf223.expensetrackerfaf.dto;
+
+import com.faf223.expensetrackerfaf.model.User;
+import lombok.AllArgsConstructor;
+import lombok.Data;
+
+@Data
+@AllArgsConstructor
+public class ExpenseCreationDTO {
+    private long expenseId;
+    private User user;
+}
diff --git a/src/main/java/com/faf223/expensetrackerfaf/dto/ExpenseDTO.java b/src/main/java/com/faf223/expensetrackerfaf/dto/ExpenseDTO.java
new file mode 100644
index 0000000..b18643a
--- /dev/null
+++ b/src/main/java/com/faf223/expensetrackerfaf/dto/ExpenseDTO.java
@@ -0,0 +1,18 @@
+package com.faf223.expensetrackerfaf.dto;
+
+import com.faf223.expensetrackerfaf.model.ExpenseCategory;
+import lombok.AllArgsConstructor;
+import lombok.Data;
+
+import java.math.BigDecimal;
+import java.time.LocalDate;
+
+@Data
+@AllArgsConstructor
+public class ExpenseDTO {
+    private long expenseId;
+    private UserDTO userDTO;
+    private ExpenseCategory expenseCategory;
+    private LocalDate date;
+    private BigDecimal amount;
+}
diff --git a/src/main/java/com/faf223/expensetrackerfaf/dto/IncomeCreationDTO.java b/src/main/java/com/faf223/expensetrackerfaf/dto/IncomeCreationDTO.java
new file mode 100644
index 0000000..e35c522
--- /dev/null
+++ b/src/main/java/com/faf223/expensetrackerfaf/dto/IncomeCreationDTO.java
@@ -0,0 +1,12 @@
+package com.faf223.expensetrackerfaf.dto;
+
+import com.faf223.expensetrackerfaf.model.User;
+import lombok.AllArgsConstructor;
+import lombok.Data;
+
+@Data
+@AllArgsConstructor
+public class IncomeCreationDTO {
+    private long incomeId;
+    private User userDTO;
+}
diff --git a/src/main/java/com/faf223/expensetrackerfaf/dto/IncomeDTO.java b/src/main/java/com/faf223/expensetrackerfaf/dto/IncomeDTO.java
new file mode 100644
index 0000000..3ee4998
--- /dev/null
+++ b/src/main/java/com/faf223/expensetrackerfaf/dto/IncomeDTO.java
@@ -0,0 +1,18 @@
+package com.faf223.expensetrackerfaf.dto;
+
+import com.faf223.expensetrackerfaf.model.IncomeCategory;
+import lombok.AllArgsConstructor;
+import lombok.Data;
+
+import java.math.BigDecimal;
+import java.time.LocalDate;
+
+@Data
+@AllArgsConstructor
+public class IncomeDTO {
+    private long incomeId;
+    private UserDTO userDTO;
+    private IncomeCategory category;
+    private LocalDate date;
+    private BigDecimal amount;
+}
diff --git a/src/main/java/com/faf223/expensetrackerfaf/dto/UserCreationDTO.java b/src/main/java/com/faf223/expensetrackerfaf/dto/UserCreationDTO.java
new file mode 100644
index 0000000..b947426
--- /dev/null
+++ b/src/main/java/com/faf223/expensetrackerfaf/dto/UserCreationDTO.java
@@ -0,0 +1,10 @@
+package com.faf223.expensetrackerfaf.dto;
+
+import lombok.AllArgsConstructor;
+import lombok.Data;
+
+@Data
+@AllArgsConstructor
+public class UserCreationDTO {
+    private String uuid;
+}
diff --git a/src/main/java/com/faf223/expensetrackerfaf/dto/UserDTO.java b/src/main/java/com/faf223/expensetrackerfaf/dto/UserDTO.java
new file mode 100644
index 0000000..9f79253
--- /dev/null
+++ b/src/main/java/com/faf223/expensetrackerfaf/dto/UserDTO.java
@@ -0,0 +1,13 @@
+package com.faf223.expensetrackerfaf.dto;
+
+import lombok.AllArgsConstructor;
+import lombok.Data;
+
+@Data
+@AllArgsConstructor
+public class UserDTO {
+    private String uuid;
+    private String name;
+    private String surname;
+    private String username;
+}
diff --git a/src/main/java/com/faf223/expensetrackerfaf/dto/mappers/ExpenseMapper.java b/src/main/java/com/faf223/expensetrackerfaf/dto/mappers/ExpenseMapper.java
new file mode 100644
index 0000000..7e91e8b
--- /dev/null
+++ b/src/main/java/com/faf223/expensetrackerfaf/dto/mappers/ExpenseMapper.java
@@ -0,0 +1,31 @@
+package com.faf223.expensetrackerfaf.dto.mappers;
+
+import com.faf223.expensetrackerfaf.dto.ExpenseCreationDTO;
+import com.faf223.expensetrackerfaf.dto.ExpenseDTO;
+import com.faf223.expensetrackerfaf.model.Expense;
+import com.faf223.expensetrackerfaf.service.ExpenseService;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.stereotype.Component;
+
+@Component
+public class ExpenseMapper {
+
+    private final ExpenseService expenseService;
+    private final UserMapper userMapper;
+
+    @Autowired
+    public ExpenseMapper(ExpenseService expenseService, UserMapper userMapper) {
+        this.expenseService = expenseService;
+        this.userMapper = userMapper;
+    }
+
+    public ExpenseDTO toDto(Expense expense) {
+        return new ExpenseDTO(expense.getExpenseId(), userMapper.toDto(expense.getUser()),
+                expense.getCategory(), expense.getDate(), expense.getAmount());
+    }
+
+    public Expense toExpense(ExpenseCreationDTO expenseDTO) {
+        return expenseService.getExpenseById(expenseDTO.getExpenseId());
+    }
+
+}
diff --git a/src/main/java/com/faf223/expensetrackerfaf/dto/mappers/IncomeMapper.java b/src/main/java/com/faf223/expensetrackerfaf/dto/mappers/IncomeMapper.java
new file mode 100644
index 0000000..91c08d3
--- /dev/null
+++ b/src/main/java/com/faf223/expensetrackerfaf/dto/mappers/IncomeMapper.java
@@ -0,0 +1,31 @@
+package com.faf223.expensetrackerfaf.dto.mappers;
+
+import com.faf223.expensetrackerfaf.dto.IncomeCreationDTO;
+import com.faf223.expensetrackerfaf.dto.IncomeDTO;
+import com.faf223.expensetrackerfaf.model.Income;
+import com.faf223.expensetrackerfaf.service.IncomeService;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.stereotype.Component;
+
+@Component
+public class IncomeMapper {
+
+    private final IncomeService incomeService;
+    private final UserMapper userMapper;
+
+    @Autowired
+    public IncomeMapper(IncomeService incomeService, UserMapper userMapper) {
+        this.incomeService = incomeService;
+        this.userMapper = userMapper;
+    }
+
+    public IncomeDTO toDto(Income income) {
+        return new IncomeDTO(income.getIncomeId(), userMapper.toDto(income.getUser()),
+                income.getCategory(), income.getDate(), income.getAmount());
+    }
+
+    public Income toIncome(IncomeCreationDTO incomeDTO) {
+        return incomeService.getIncomeById(incomeDTO.getIncomeId());
+    }
+
+}
diff --git a/src/main/java/com/faf223/expensetrackerfaf/dto/mappers/UserMapper.java b/src/main/java/com/faf223/expensetrackerfaf/dto/mappers/UserMapper.java
new file mode 100644
index 0000000..a403a24
--- /dev/null
+++ b/src/main/java/com/faf223/expensetrackerfaf/dto/mappers/UserMapper.java
@@ -0,0 +1,28 @@
+package com.faf223.expensetrackerfaf.dto.mappers;
+
+import com.faf223.expensetrackerfaf.dto.UserCreationDTO;
+import com.faf223.expensetrackerfaf.dto.UserDTO;
+import com.faf223.expensetrackerfaf.model.User;
+import com.faf223.expensetrackerfaf.service.UserService;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.stereotype.Component;
+
+@Component
+public class UserMapper {
+
+    private final UserService userService;
+
+    @Autowired
+    public UserMapper(UserService userService) {
+        this.userService = userService;
+    }
+
+    public UserDTO toDto(User user) {
+        return new UserDTO(user.getUuid(), user.getName(), user.getSurname(), user.getUsername());
+    }
+
+    public User toUser(UserCreationDTO userDTO) {
+        return userService.getUserById(userDTO.getUuid());
+    }
+
+}
diff --git a/src/main/java/com/faf223/expensetrackerfaf/model/User.java b/src/main/java/com/faf223/expensetrackerfaf/model/User.java
index b5a30a9..0460db9 100644
--- a/src/main/java/com/faf223/expensetrackerfaf/model/User.java
+++ b/src/main/java/com/faf223/expensetrackerfaf/model/User.java
@@ -10,7 +10,7 @@ import lombok.Data;
 public class User {
     @Id
     @Column(table = "users", name = "user_uuid")
-    private String userUuid;
+    private String uuid;
 
     private String name;
     private String surname;
diff --git a/src/main/java/com/faf223/expensetrackerfaf/repository/ExpenseRepository.java b/src/main/java/com/faf223/expensetrackerfaf/repository/ExpenseRepository.java
index 4cd39d0..38fb2fb 100644
--- a/src/main/java/com/faf223/expensetrackerfaf/repository/ExpenseRepository.java
+++ b/src/main/java/com/faf223/expensetrackerfaf/repository/ExpenseRepository.java
@@ -8,5 +8,5 @@ import java.util.List;
 
 @Repository
 public interface ExpenseRepository extends JpaRepository<Expense, Long> {
-    List<Expense> findByUserUserUuid(String userUuid);
+    List<Expense> findByUserUuid(String userUuid);
 }
diff --git a/src/main/java/com/faf223/expensetrackerfaf/repository/IncomeRepository.java b/src/main/java/com/faf223/expensetrackerfaf/repository/IncomeRepository.java
index 9a1a592..2f199af 100644
--- a/src/main/java/com/faf223/expensetrackerfaf/repository/IncomeRepository.java
+++ b/src/main/java/com/faf223/expensetrackerfaf/repository/IncomeRepository.java
@@ -8,5 +8,5 @@ import java.util.List;
 
 @Repository
 public interface IncomeRepository extends JpaRepository<Income, Long> {
-    List<Income> findByUserUserUuid(String userUuid);
+    List<Income> findByUserUuid(String userUuid);
 }
diff --git a/src/main/java/com/faf223/expensetrackerfaf/service/ExpenseService.java b/src/main/java/com/faf223/expensetrackerfaf/service/ExpenseService.java
index 56ef226..942c5a1 100644
--- a/src/main/java/com/faf223/expensetrackerfaf/service/ExpenseService.java
+++ b/src/main/java/com/faf223/expensetrackerfaf/service/ExpenseService.java
@@ -22,10 +22,14 @@ public class ExpenseService {
     }
 
     public List<Expense> getExpensesByUserId(String userUuid) {
-        return expenseRepository.findByUserUserUuid(userUuid);
+        return expenseRepository.findByUserUuid(userUuid);
     }
 
     public List<Expense> getExpenses() {
         return expenseRepository.findAll();
     }
+
+    public Expense getExpenseById(long id) {
+        return expenseRepository.findById(id).orElse(null);
+    }
 }
\ No newline at end of file
diff --git a/src/main/java/com/faf223/expensetrackerfaf/service/IncomeService.java b/src/main/java/com/faf223/expensetrackerfaf/service/IncomeService.java
index 65347fb..cde77d0 100644
--- a/src/main/java/com/faf223/expensetrackerfaf/service/IncomeService.java
+++ b/src/main/java/com/faf223/expensetrackerfaf/service/IncomeService.java
@@ -26,6 +26,10 @@ public class IncomeService {
     }
 
     public List<Income> getIncomesByUserId(String userUuid) {
-        return incomeRepository.findByUserUserUuid(userUuid);
+        return incomeRepository.findByUserUuid(userUuid);
+    }
+
+    public Income getIncomeById(long id) {
+        return incomeRepository.findById(id).orElse(null);
     }
 }