diff --git a/back/Contracts/DTOs/UserDTO.cs b/back/Contracts/DTOs/UserDTO.cs
index abf5f99..e312313 100644
--- a/back/Contracts/DTOs/UserDTO.cs
+++ b/back/Contracts/DTOs/UserDTO.cs
@@ -2,8 +2,8 @@ namespace Contracts.DTO;
 
 public class UserDto
 {
-    public Guid? Id { get; set; }
-    public string? Username { get; set; }
-    public string? Password { get; set; }
-    public decimal? Balance { get; set; }
+    public Guid Id { get; set; }
+    public string Name { get; set; } = string.Empty;
+    public string Password { get; set; } = string.Empty;
+    public decimal Balance { get; set; }
 }
\ No newline at end of file
diff --git a/back/Contracts/DTOs/UserLoginDTO.cs b/back/Contracts/DTOs/UserLoginDTO.cs
new file mode 100644
index 0000000..73210e9
--- /dev/null
+++ b/back/Contracts/DTOs/UserLoginDTO.cs
@@ -0,0 +1,7 @@
+namespace Contracts.DTO;
+
+public class UserLoginDTO
+{
+    public string Name { get; set; } = string.Empty;
+    public string Password { get; set; } = string.Empty;
+}
\ No newline at end of file
diff --git a/back/Contracts/Mappers/UserMapper.cs b/back/Contracts/Mappers/UserMapper.cs
new file mode 100644
index 0000000..a32afed
--- /dev/null
+++ b/back/Contracts/Mappers/UserMapper.cs
@@ -0,0 +1,16 @@
+using Contracts.DTO;
+using Contracts.ViewModels;
+
+namespace Contracts.Mappers;
+
+public static class UserMapper
+{
+    public static UserViewModel ToView(this UserDto user) 
+        => new() 
+        { 
+            Id = user.Id, 
+            Name = user.Name, 
+            Balance = user.Balance 
+        };
+    
+}
\ No newline at end of file
diff --git a/back/Contracts/Repositories/IUserRepo.cs b/back/Contracts/Repositories/IUserRepo.cs
index 3785e5e..926450c 100644
--- a/back/Contracts/Repositories/IUserRepo.cs
+++ b/back/Contracts/Repositories/IUserRepo.cs
@@ -5,7 +5,7 @@ namespace Contracts.Repositories;
 
 public interface IUserRepo
 {
-    public Task<UserDto> Get(UserSearch search);
+    public Task<UserDto?> Get(UserSearch search);
     public Task<UserDto> Create(UserDto user);
     public Task<UserDto> Update(UserDto user);
     public Task<UserDto> Delete(UserSearch search);
diff --git a/back/Contracts/SearchModels/UserSearch.cs b/back/Contracts/SearchModels/UserSearch.cs
index 7165750..7ea4178 100644
--- a/back/Contracts/SearchModels/UserSearch.cs
+++ b/back/Contracts/SearchModels/UserSearch.cs
@@ -3,4 +3,5 @@ namespace Contracts.SearchModels;
 public class UserSearch
 {
     public Guid? Id { get; set; }
+    public string? Name { get; set; }
 }
\ No newline at end of file
diff --git a/back/Contracts/Services/IAuthService.cs b/back/Contracts/Services/IAuthService.cs
index d6e5983..03548f7 100644
--- a/back/Contracts/Services/IAuthService.cs
+++ b/back/Contracts/Services/IAuthService.cs
@@ -1,12 +1,11 @@
 using Contracts.DTO;
+using Contracts.SearchModels;
 using Contracts.ViewModels;
 
 namespace Contracts.Services;
 
 public interface IAuthService
 {
-    public Task<UserViewModel> Login();
+    public Task<UserViewModel> Login(UserLoginDTO loginData);
     public Task<UserViewModel> Register(UserDto user);
-    public Task<UserViewModel> UpdateUserData(UserDto user);
-    public Task<UserViewModel> Delete(Guid id);
 }
\ No newline at end of file
diff --git a/back/Contracts/Services/IUserService.cs b/back/Contracts/Services/IUserService.cs
new file mode 100644
index 0000000..736d3bf
--- /dev/null
+++ b/back/Contracts/Services/IUserService.cs
@@ -0,0 +1,12 @@
+using Contracts.DTO;
+using Contracts.SearchModels;
+using Contracts.ViewModels;
+
+namespace Contracts.Services;
+
+public interface IUserService
+{
+    public Task<UserViewModel> GetDetails(UserSearch search);
+    public Task<UserViewModel> UpdateUserData(UserDto user);
+    public Task<UserViewModel> Delete(UserSearch search);
+}
\ No newline at end of file
diff --git a/back/Services/Domain/AuthService.cs b/back/Services/Domain/AuthService.cs
new file mode 100644
index 0000000..4d59a79
--- /dev/null
+++ b/back/Services/Domain/AuthService.cs
@@ -0,0 +1,49 @@
+using Contracts.DTO;
+using Contracts.Mappers;
+using Contracts.Repositories;
+using Contracts.SearchModels;
+using Contracts.Services;
+using Contracts.ViewModels;
+using Services.Support.Exceptions;
+
+namespace Services.Domain;
+
+public class AuthService : IAuthService
+{
+    private readonly IUserRepo _userRepo;
+
+    public AuthService(IUserRepo userRepo)
+    {
+        _userRepo = userRepo;
+    }
+
+    public async Task<UserViewModel> Login(UserLoginDTO loginData)
+    {
+        if (loginData == null || string.IsNullOrWhiteSpace(loginData.Name)
+            || string.IsNullOrWhiteSpace(loginData.Password))
+        {
+            throw new ArgumentException("Неверные данные для входа");
+        }
+
+        var user = await _userRepo.Get(new UserSearch() { Name = loginData.Name });
+        if (user == null)
+        {
+            throw new UserNotFoundException($"Пользователь {loginData.Name} не найден");
+        }
+
+        return user.ToView();
+    }
+
+    public async Task<UserViewModel> Register(UserDto user)
+    {
+        var existingUser = await _userRepo.Get(new UserSearch() { Name = user.Name });
+        if (existingUser != null)
+        {
+            throw new AlreadyExistsException("Такой пользователь уже существует");
+        }
+        
+        var createdUser = await _userRepo.Create(user);
+        
+        return createdUser.ToView();
+    }
+}
diff --git a/back/Services/Domain/UserService.cs b/back/Services/Domain/UserService.cs
new file mode 100644
index 0000000..e54904d
--- /dev/null
+++ b/back/Services/Domain/UserService.cs
@@ -0,0 +1,47 @@
+using Contracts.DTO;
+using Contracts.Mappers;
+using Contracts.Repositories;
+using Contracts.SearchModels;
+using Contracts.Services;
+using Contracts.ViewModels;
+using Services.Support.Exceptions;
+
+namespace Services.Domain;
+
+public class UserService : IUserService
+{
+    private readonly IUserRepo _userRepo;
+
+    public UserService(IUserRepo userRepo)
+    {
+        _userRepo = userRepo;
+    }
+
+    public async Task<UserViewModel> Delete(UserSearch search)
+    {
+        var user = await _userRepo.Delete(search);
+        return user.ToView();
+    }
+
+    public async Task<UserViewModel> GetDetails(UserSearch search)
+    {
+        var user = await _userRepo.Get(search);
+        if (user == null) 
+        {
+            throw new UserNotFoundException($"Пользователь {search.Name} не найден");
+        }
+        return user.ToView();
+    }
+
+    public async Task<UserViewModel> UpdateUserData(UserDto user)
+    {
+        var existingUser = await _userRepo.Get(new UserSearch() { Name = user.Name });
+        if (existingUser == null)
+        {
+            throw new UserNotFoundException($"Пользователь {user.Name} не найден");
+        }
+        
+        var updatedUser = await _userRepo.Update(user);
+        return updatedUser.ToView();
+    }
+}
diff --git a/back/Services/Services.csproj b/back/Services/Services.csproj
index fa71b7a..3c22415 100644
--- a/back/Services/Services.csproj
+++ b/back/Services/Services.csproj
@@ -1,5 +1,9 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
+  <ItemGroup>
+    <ProjectReference Include="..\Contracts\Contracts.csproj" />
+  </ItemGroup>
+
   <PropertyGroup>
     <TargetFramework>net8.0</TargetFramework>
     <ImplicitUsings>enable</ImplicitUsings>
diff --git a/back/Services/Support/Exceptions/AlreadyExistsException.cs b/back/Services/Support/Exceptions/AlreadyExistsException.cs
new file mode 100644
index 0000000..8577218
--- /dev/null
+++ b/back/Services/Support/Exceptions/AlreadyExistsException.cs
@@ -0,0 +1,9 @@
+namespace Services.Support.Exceptions;
+
+public class AlreadyExistsException : Exception
+{
+    public AlreadyExistsException(string message) : base(message) { }
+    
+    public AlreadyExistsException(string message, Exception innerException) 
+        : base(message, innerException) { }
+}
\ No newline at end of file
diff --git a/back/Services/Support/Exceptions/UserNotFoundException.cs b/back/Services/Support/Exceptions/UserNotFoundException.cs
new file mode 100644
index 0000000..df152a1
--- /dev/null
+++ b/back/Services/Support/Exceptions/UserNotFoundException.cs
@@ -0,0 +1,11 @@
+using Contracts.SearchModels;
+
+namespace Services.Support.Exceptions;
+
+public class UserNotFoundException : Exception
+{
+    public UserNotFoundException(string message) 
+        : base(message) { }
+    public UserNotFoundException(string message, Exception innerException) 
+        : base(message, innerException) { }
+}
\ No newline at end of file