diff --git a/.gitignore b/.gitignore
index 986ec50..c50af21 100644
--- a/.gitignore
+++ b/.gitignore
@@ -482,3 +482,7 @@ $RECYCLE.BIN/
 
 # Vim temporary swap files
 *.swp
+
+# App data files and data for dev
+/data
+/data_dev
diff --git a/OptixServe.Api/Configuration/AppSettings.cs b/OptixServe.Api/Configuration/AppSettings.cs
new file mode 100644
index 0000000..7a53c2f
--- /dev/null
+++ b/OptixServe.Api/Configuration/AppSettings.cs
@@ -0,0 +1,34 @@
+namespace OptixServe.Api.Configuration;
+
+public record OptixServeSettings
+{
+    public ApiSettings? Api { get; set; } = new();
+    public DatabaseSettings? Database { get; set; } = new();
+    public JwtSettings? Jwt { get; set; } = new();
+}
+
+public record ApiSettings
+{
+    public string? Listen { get; set; } = "127.0.0.1";
+    public int? Port { get; set; } = 10086;
+}
+
+public record JwtSettings
+{
+    public string Secret { get; set; } = string.Empty;
+    public string Issuer { get; set; } = "OptixServe";
+    public string Audience { get; set; } = "OptixServeUsers";
+    public int TokenExpirationMinutes { get; set; } = 60;
+}
+
+public enum DatabaseType
+{
+    Sqlite,
+    MySQL
+}
+
+public record DatabaseSettings
+{
+    public DatabaseType Type { get; set; } = DatabaseType.Sqlite;
+    public string? Host { get; set; }
+}
\ No newline at end of file
diff --git a/OptixServe.Api/Configuration/ConfigurationHelper.cs b/OptixServe.Api/Configuration/ConfigurationHelper.cs
new file mode 100644
index 0000000..4c222e3
--- /dev/null
+++ b/OptixServe.Api/Configuration/ConfigurationHelper.cs
@@ -0,0 +1,27 @@
+using System;
+
+namespace OptixServe.Api.Configuration;
+
+public static class ConfigurationHelper
+{
+    public static IConfigurationBuilder CreateDefaultBuilder()
+    {
+        var aspEnv = Environment.GetEnvironmentVariable("ASPNETCORE_ENVIRONMENT");
+        var netEnv = Environment.GetEnvironmentVariable("DOTNET_ENVIRONMENT");
+        // Console.WriteLine($"ASPNETCORE_ENVIRONMENT: {aspEnv}, DOTNET_ENVIRONMENT: {netEnv}");
+        var env = aspEnv ?? netEnv ?? null;
+
+        var builder = new ConfigurationBuilder()
+            .SetBasePath(Directory.GetCurrentDirectory())
+            .AddJsonFile("appsettings.json", optional: true)
+            .AddJsonFile("config.json", optional: true);
+        
+        if (env != null)
+        {
+            builder.AddJsonFile($"appsettings.{env}.json", optional: true)
+                .AddJsonFile($"config.{env}.json", optional: true);
+        }
+
+        return builder;
+    }
+}
\ No newline at end of file
diff --git a/OptixServe.Api/Dtos/Auth.cs b/OptixServe.Api/Dtos/Auth.cs
new file mode 100644
index 0000000..c867991
--- /dev/null
+++ b/OptixServe.Api/Dtos/Auth.cs
@@ -0,0 +1,12 @@
+namespace OptixServe.Api.Dtos;
+
+public record LoginRequestDto
+{
+    public string? UserName { get; set; }
+    public string? Password { get; set; }
+}
+
+public record LoginResponseDto
+{
+    public string? Token { get; set; }
+}
\ No newline at end of file
diff --git a/OptixServe.Api/Dtos/Error.cs b/OptixServe.Api/Dtos/Error.cs
new file mode 100644
index 0000000..eb1d505
--- /dev/null
+++ b/OptixServe.Api/Dtos/Error.cs
@@ -0,0 +1,6 @@
+namespace OptixServe.Api.Dtos;
+
+public record CommonErrorDto
+{
+    public string? Message { get; set; }
+}
\ No newline at end of file
diff --git a/OptixServe.Api/Endpoints/UserEndpoint.cs b/OptixServe.Api/Endpoints/UserEndpoint.cs
index add9286..24abe86 100644
--- a/OptixServe.Api/Endpoints/UserEndpoint.cs
+++ b/OptixServe.Api/Endpoints/UserEndpoint.cs
@@ -1,32 +1,61 @@
 using System.Text.Json.Serialization;
+using OptixServe.Core.Services;
 using OptixServe.Api.Dtos;
+using OptixServe.Api.Services;
+using Microsoft.AspNetCore.Authorization;
 
 namespace OptixServe.Api.Endpoints;
 
 
 [JsonSerializable(typeof(UserDto))]
 [JsonSerializable(typeof(IEnumerable<UserDto>))]
+[JsonSerializable(typeof(LoginRequestDto))]
+[JsonSerializable(typeof(LoginResponseDto))] // For returning the token string
 public partial class UserJsonContext : JsonSerializerContext { }
 
 public static class UserEndpoint
 {
-    public static IEnumerable<UserDto> GetUsers()
+    public static void Register(RouteGroupBuilder parentGroup)
     {
-        return [
-            new() {Id="1234", UserName = "xxx"},
-            new() {Id="5678", UserName = "yyy"},
-        ];
+        var group = parentGroup.MapGroup("/users");
+
+        group.MapPost("/login", LoginUser);
+        group.MapGet("/", GetAllUsers).RequireAuthorization();
+        group.MapGet("/{id}", GetUserById).RequireAuthorization();
     }
 
-    public static void Register(WebApplication app)
+    public static IResult LoginUser(LoginRequestDto loginRequest, IUserService userService, ITokenService tokenService)
     {
-        var group = app.MapGroup("/users");
+        if (string.IsNullOrEmpty(loginRequest.UserName) || string.IsNullOrEmpty(loginRequest.Password))
+        {
+            return Results.BadRequest("Username and password are required.");
+        }
 
-        group.MapGet("/", GetAllUsers);
+        // Password hashing and salting will be implemented later.
+        var user = userService.GetUserByUsername(loginRequest.UserName);
+
+        if (user == null || user.Password != loginRequest.Password)
+        {
+            return Results.Unauthorized();
+        }
+
+        var token = tokenService.GenerateToken(user);
+        return Results.Ok(new LoginResponseDto { Token = token });
     }
 
-    public static IResult GetAllUsers()
+    public static IResult GetAllUsers(IUserService userService)
     {
-        return Results.Ok(GetUsers());
+        var users = userService.GetUsers()
+            .Select(u => new UserDto { Id = u.Id, UserName = u.UserName });
+        return Results.Ok(users);
     }
-}
\ No newline at end of file
+
+    public static IResult GetUserById(string id, IUserService userService)
+    {
+        var user = userService.GetUserById(id);
+        if (user == null)
+            return Results.NotFound();
+
+        return Results.Ok(new UserDto { Id = user.Id, UserName = user.UserName });
+    }
+}
diff --git a/OptixServe.Api/Endpoints/VersionEndpoint.cs b/OptixServe.Api/Endpoints/VersionEndpoint.cs
new file mode 100644
index 0000000..6eb01ec
--- /dev/null
+++ b/OptixServe.Api/Endpoints/VersionEndpoint.cs
@@ -0,0 +1,35 @@
+using System.Text.Json.Serialization;
+using Microsoft.Extensions.Options;
+using OptixServe.Api.Configuration;
+using OptixServe.Api.Dtos;
+
+namespace OptixServe.Api.Endpoints;
+
+
+[JsonSerializable(typeof(string))]
+[JsonSerializable(typeof(CommonErrorDto))]
+public partial class VersionJsonContext : JsonSerializerContext { }
+
+
+/// <summary>
+/// This is a endpoint ONLY FOR TEST!
+/// Should not expect ANY stable behavior on it!
+/// </summary>
+public static class VersionEndpoint
+{
+    public static void Register(RouteGroupBuilder parentGroup)
+    {
+        var group = parentGroup.MapGroup("/version");
+
+        group.MapGet("/", () => "v1");
+        group.MapGet("/test/dbconfig", (IOptions<OptixServeSettings> appSettings) =>
+        {
+            var dbType = appSettings.Value.Database?.Type;
+            var dbHost = appSettings.Value.Database?.Host;
+            return Results.Ok(new CommonErrorDto
+            {
+                Message = $"Set up {dbType} database on {dbHost}"
+            });
+        });
+    }
+}
\ No newline at end of file
diff --git a/OptixServe.Api/OptixServe.Api.csproj b/OptixServe.Api/OptixServe.Api.csproj
index 3815467..c3e18e4 100644
--- a/OptixServe.Api/OptixServe.Api.csproj
+++ b/OptixServe.Api/OptixServe.Api.csproj
@@ -1,11 +1,17 @@
 <Project Sdk="Microsoft.NET.Sdk.Web">
 
-  <ItemGroup>
-    <ProjectReference Include="..\OptixServe.Core\OptixServe.Core.csproj" />
+  <ItemGroup>
+    <ProjectReference Include="..\OptixServe.Core\OptixServe.Core.csproj" />
   </ItemGroup>
 
-  <ItemGroup>
-    <PackageReference Include="System.CommandLine" Version="2.0.0-beta5.25306.1" />
+  <ItemGroup>
+    <PackageReference Include="Microsoft.AspNetCore.Authentication.JwtBearer" Version="9.0.6" />
+    <PackageReference Include="System.CommandLine" Version="2.0.0-beta5.25306.1" />
+    <PackageReference Include="Microsoft.EntityFrameworkCore.Design" Version="9.0.6">
+      <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
+      <PrivateAssets>all</PrivateAssets>
+    </PackageReference>
+    <PackageReference Include="Microsoft.EntityFrameworkCore.Sqlite" Version="9.0.6" />
   </ItemGroup>
 
   <PropertyGroup>
@@ -13,7 +19,7 @@
     <Nullable>enable</Nullable>
     <ImplicitUsings>enable</ImplicitUsings>
     <InvariantGlobalization>true</InvariantGlobalization>
-    <PublishAot>true</PublishAot>
+    <PublishAot>false</PublishAot>
   </PropertyGroup>
 
 </Project>
diff --git a/OptixServe.Api/Program.cs b/OptixServe.Api/Program.cs
index 5f29100..6d25783 100644
--- a/OptixServe.Api/Program.cs
+++ b/OptixServe.Api/Program.cs
@@ -1,5 +1,13 @@
 using System.CommandLine;
+using System.Text;
+using Microsoft.AspNetCore.Authentication.JwtBearer;
+using Microsoft.IdentityModel.Tokens;
+using OptixServe.Api.Configuration;
 using OptixServe.Api.Endpoints;
+using OptixServe.Api.Services;
+using OptixServe.Core.Data;
+using OptixServe.Core.Services;
+using OptixServe.Api.Utilites;
 
 class Program
 {
@@ -41,10 +49,22 @@ class Program
             var configFile = parseResult.GetValue(configOption);
             builder.AddConfigurationWithCommand(configFile);
 
+            builder.RegisterServices();
             builder.RegiserJsonContext();
 
             var app = builder.Build();
-            app.RegisterEndpoints();
+
+            app.UseAuthentication();
+            app.UseAuthorization();
+
+            using (var scope = app.Services.CreateScope())
+            {
+                var initializer = scope.ServiceProvider.GetRequiredService<DbInitializer>();
+                initializer.Initialize();
+            }
+
+            var apiGroup = app.MapGroup("api/v1");
+            StartupHelper.RegisterEndpoints(apiGroup);
 
             app.Run();
         });
@@ -59,29 +79,8 @@ class Program
 /// <summary>
 /// Contains extension methods for WebApplicationBuilder and WebApplication
 /// </summary>
-static class ExtensionMethods
+static class StartupHelper
 {
-    /// <summary>
-    /// Registers all API endpoints
-    /// </summary>
-    /// <param name="app">WebApplication instance</param>
-    public static void RegisterEndpoints(this WebApplication app)
-    {
-        UserEndpoint.Register(app);
-    }
-
-    /// <summary>
-    /// Configures JSON serialization options with custom context
-    /// </summary>
-    /// <param name="builder">WebApplicationBuilder instance</param>
-    public static void RegiserJsonContext(this WebApplicationBuilder builder)
-    {
-        builder.Services.ConfigureHttpJsonOptions(options =>
-        {
-            options.SerializerOptions.TypeInfoResolverChain.Add(UserJsonContext.Default);
-        });
-    }
-
     /// <summary>
     /// Adds configuration sources to the application builder
     /// </summary>
@@ -105,4 +104,78 @@ static class ExtensionMethods
 
         builder.Configuration.AddConfiguration(configurationBuilder.Build());
     }
+
+    /// <summary>
+    /// Configures DbContext services
+    /// </summary>
+    /// <param name="services"></param>
+    /// <param name="configuration"></param>
+    /// <returns></returns>
+    public static IServiceCollection AddAppDatabase(this IServiceCollection services, DatabaseSettings dbSettings)
+    {
+        services.AddDbContext<AppDbContext>(options => DatabaseHelper.ConfigureDbContext(options, dbSettings));
+        return services;
+    }
+
+    /// <summary>
+    /// Configures services for DI
+    /// </summary>
+    /// <param name="builder">WebApplicationBuilder instance</param>
+    public static void RegisterServices(this WebApplicationBuilder builder)
+    {
+        // Add configuration class
+        var optixSettigns = builder.Configuration.GetSection("OptixServe");
+        var onConfigSettings = optixSettigns.Get<OptixServeSettings>();
+        builder.Services.Configure<OptixServeSettings>(optixSettigns);
+
+        // Add DBContext class
+        builder.Services.AddAppDatabase(onConfigSettings?.Database!);
+        builder.Services.AddScoped<DbInitializer>();
+
+        // Application services
+        builder.Services.AddScoped<IUserService, UserService>();
+        builder.Services.AddScoped<ITokenService, TokenService>();
+
+        // Add Authentication and Authorization
+        builder.Services.AddAuthentication(JwtBearerDefaults.AuthenticationScheme)
+            .AddJwtBearer(options =>
+            {
+                var jwtSettings = onConfigSettings?.Jwt ?? throw new ArgumentNullException(nameof(builder), "JWT settings are not configured.");
+                options.TokenValidationParameters = new TokenValidationParameters
+                {
+                    ValidateIssuer = true,
+                    ValidateAudience = true,
+                    ValidateLifetime = true,
+                    ValidateIssuerSigningKey = true,
+                    ValidIssuer = jwtSettings.Issuer,
+                    ValidAudience = jwtSettings.Audience,
+                    IssuerSigningKey = new SymmetricSecurityKey(Encoding.UTF8.GetBytes(jwtSettings.Secret))
+                };
+            });
+        builder.Services.AddAuthorization();
+    }
+
+    /// <summary>
+    /// Configures JSON serialization options with custom context
+    /// </summary>
+    /// <param name="builder">WebApplicationBuilder instance</param>
+    public static void RegiserJsonContext(this WebApplicationBuilder builder)
+    {
+        builder.Services.ConfigureHttpJsonOptions(options =>
+        {
+            options.SerializerOptions.TypeInfoResolverChain.Add(UserJsonContext.Default);
+            options.SerializerOptions.TypeInfoResolverChain.Add(VersionJsonContext.Default);
+        });
+    }
+
+    /// <summary>
+    /// Registers all API endpoints
+    /// </summary>
+    /// <param name="rootGroup">Root RouteGroupBuilder instance</param>
+    public static void RegisterEndpoints(RouteGroupBuilder rootGroup)
+    {
+        UserEndpoint.Register(rootGroup);
+        VersionEndpoint.Register(rootGroup);
+    }
+
 }
\ No newline at end of file
diff --git a/OptixServe.Api/Services/TokenService.cs b/OptixServe.Api/Services/TokenService.cs
new file mode 100644
index 0000000..f124f92
--- /dev/null
+++ b/OptixServe.Api/Services/TokenService.cs
@@ -0,0 +1,44 @@
+using System.IdentityModel.Tokens.Jwt;
+using System.Security.Claims;
+using System.Text;
+using Microsoft.Extensions.Options;
+using Microsoft.IdentityModel.Tokens;
+using OptixServe.Api.Configuration;
+using OptixServe.Core.Models;
+
+namespace OptixServe.Api.Services;
+
+public interface ITokenService
+{
+    public string GenerateToken(User user);
+}
+
+public class TokenService(IOptions<OptixServeSettings> optixServeSettings) : ITokenService
+{
+    private readonly JwtSettings _jwtSettings = optixServeSettings.Value.Jwt ?? throw new ArgumentNullException(nameof(optixServeSettings), "JWT settings are not configured.");
+
+    public string GenerateToken(User user)
+    {
+        var tokenHandler = new JwtSecurityTokenHandler();
+        var key = Encoding.ASCII.GetBytes(_jwtSettings.Secret);
+
+        var claims = new List<Claim>
+        {
+            new (ClaimTypes.NameIdentifier, user.Id.ToString()),
+            new (ClaimTypes.Name, user.UserName)
+            // Add roles if applicable: new Claim(ClaimTypes.Role, user.Role)
+        };
+
+        var tokenDescriptor = new SecurityTokenDescriptor
+        {
+            Subject = new ClaimsIdentity(claims),
+            Expires = DateTime.UtcNow.AddMinutes(_jwtSettings.TokenExpirationMinutes),
+            Issuer = _jwtSettings.Issuer,
+            Audience = _jwtSettings.Audience,
+            SigningCredentials = new SigningCredentials(new SymmetricSecurityKey(key), SecurityAlgorithms.HmacSha256Signature)
+        };
+
+        var token = tokenHandler.CreateToken(tokenDescriptor);
+        return tokenHandler.WriteToken(token);
+    }
+}
\ No newline at end of file
diff --git a/OptixServe.Api/Utilites/DatabaseHelper.cs b/OptixServe.Api/Utilites/DatabaseHelper.cs
new file mode 100644
index 0000000..3107d66
--- /dev/null
+++ b/OptixServe.Api/Utilites/DatabaseHelper.cs
@@ -0,0 +1,34 @@
+using Microsoft.EntityFrameworkCore;
+using OptixServe.Api.Configuration;
+using OptixServe.Core.Data;
+
+namespace OptixServe.Api.Utilites;
+
+public static class DatabaseHelper
+{
+    public static string BuildConnectionString(DatabaseSettings dbSettings)
+    {
+        return dbSettings.Type switch
+        {
+            DatabaseType.Sqlite => $"Data Source={dbSettings.Host ?? "optixserve.db"}",
+            DatabaseType.MySQL => throw new NotSupportedException("MySQL connection is not yet implemented"),
+            _ => throw new NotSupportedException($"Database type {dbSettings.Type} is not supported")
+        };
+    }
+
+    public static void ConfigureDbContext(DbContextOptionsBuilder options, DatabaseSettings dbSettings)
+    {
+        if (dbSettings?.Type == DatabaseType.Sqlite)
+        {
+            var dbPath = dbSettings.Host ?? "optixserve.db";
+            var connectionString = $"Data Source={dbPath}";
+
+            options.UseSqlite(connectionString, b => b.MigrationsAssembly("OptixServe.Api"));
+
+        }
+        else
+        {
+            throw new NotImplementedException("Only SQLite database is currently supported");
+        }
+    }
+}
\ No newline at end of file
diff --git a/OptixServe.Api/Utilites/DesignTimeDbContextFactory.cs b/OptixServe.Api/Utilites/DesignTimeDbContextFactory.cs
new file mode 100644
index 0000000..f9d01d8
--- /dev/null
+++ b/OptixServe.Api/Utilites/DesignTimeDbContextFactory.cs
@@ -0,0 +1,20 @@
+using Microsoft.EntityFrameworkCore;
+using Microsoft.EntityFrameworkCore.Design;
+using OptixServe.Api.Configuration;
+using OptixServe.Core.Data;
+
+namespace OptixServe.Api.Utilites;
+
+public class DesignTimeDbContextFactory : IDesignTimeDbContextFactory<AppDbContext>
+{
+    public AppDbContext CreateDbContext(string[] args)
+    {
+        var configuration = ConfigurationHelper.CreateDefaultBuilder().Build();
+
+        var dbSettings = configuration.GetSection("OptixServe:Database").Get<DatabaseSettings>()!;
+        var optionsBuilder = new DbContextOptionsBuilder<AppDbContext>();
+        DatabaseHelper.ConfigureDbContext(optionsBuilder, dbSettings);
+
+        return new AppDbContext(optionsBuilder.Options);
+    }
+}
\ No newline at end of file
diff --git a/OptixServe.Api/appsettings.json b/OptixServe.Api/appsettings.json
index 4d56694..e4a86f3 100644
--- a/OptixServe.Api/appsettings.json
+++ b/OptixServe.Api/appsettings.json
@@ -5,5 +5,21 @@
       "Microsoft.AspNetCore": "Warning"
     }
   },
-  "AllowedHosts": "*"
-}
+  "AllowedHosts": "*",
+  "OptixServe": {
+    "Api": {
+      "Listen": "0.0.0.0",
+      "Port": "54321"
+    },
+    "Database": {
+      "Type": "Sqlite",
+      "Host": "optixserve.db"
+    },
+    "Jwt": {
+      "Secret": "YOUR_SECRET_KEY_HERE_DO_NOT_SHARE_THIS_AND_MAKE_IT_LONG_ENOUGH",
+      "Issuer": "OptixServe",
+      "Audience": "OptixServeUsers",
+      "TokenExpirationMinutes": 60
+    }
+  }
+}
\ No newline at end of file
diff --git a/OptixServe.Core/Data/AppDbContext.cs b/OptixServe.Core/Data/AppDbContext.cs
new file mode 100644
index 0000000..2116fc3
--- /dev/null
+++ b/OptixServe.Core/Data/AppDbContext.cs
@@ -0,0 +1,21 @@
+using Microsoft.EntityFrameworkCore;
+using OptixServe.Core.Models;
+
+namespace OptixServe.Core.Data;
+
+public class AppDbContext(DbContextOptions options) : DbContext(options)
+{
+    public DbSet<User> Users { get; set; } = null!;
+
+    protected override void OnModelCreating(ModelBuilder modelBuilder)
+    {
+        modelBuilder.Entity<User>(user =>
+        {
+            user.HasKey(u => u.Id);
+        });
+
+        modelBuilder.Entity<User>().HasData([
+            new() {Id = "1", UserName = "admin", Password = "admin12345"}
+        ]);
+    }
+}
\ No newline at end of file
diff --git a/OptixServe.Core/Data/DbInitializer.cs b/OptixServe.Core/Data/DbInitializer.cs
new file mode 100644
index 0000000..bec11cc
--- /dev/null
+++ b/OptixServe.Core/Data/DbInitializer.cs
@@ -0,0 +1,11 @@
+namespace OptixServe.Core.Data;
+
+public class DbInitializer(AppDbContext dbContext)
+{
+    private readonly AppDbContext _context = dbContext;
+
+    public void Initialize()
+    {
+        _context.Database.EnsureCreated();
+    }
+}
\ No newline at end of file
diff --git a/OptixServe.Core/Models/User.cs b/OptixServe.Core/Models/User.cs
index 671e88e..3dbd0b4 100644
--- a/OptixServe.Core/Models/User.cs
+++ b/OptixServe.Core/Models/User.cs
@@ -1,8 +1,15 @@
 namespace OptixServe.Core.Models;
 
+public enum PrivilegeGroup
+{
+    Admin,
+    User,
+}
+
 public record User
 {
     public required string Id { get; set; }
     public required string UserName { get; set; }
-    public required string Password { get; set; }
+    public string? Password { get; set; }
+    public PrivilegeGroup PrivilegeGroup { get; set; } = PrivilegeGroup.User;
 }
\ No newline at end of file
diff --git a/OptixServe.Core/OptixServe.Core.csproj b/OptixServe.Core/OptixServe.Core.csproj
index 125f4c9..354caa7 100644
--- a/OptixServe.Core/OptixServe.Core.csproj
+++ b/OptixServe.Core/OptixServe.Core.csproj
@@ -6,4 +6,8 @@
     <Nullable>enable</Nullable>
   </PropertyGroup>
 
+  <ItemGroup>
+    <PackageReference Include="Microsoft.EntityFrameworkCore" Version="9.0.6" />
+  </ItemGroup>
+
 </Project>
diff --git a/OptixServe.Core/Services/UserService.cs b/OptixServe.Core/Services/UserService.cs
new file mode 100644
index 0000000..394f05c
--- /dev/null
+++ b/OptixServe.Core/Services/UserService.cs
@@ -0,0 +1,31 @@
+using OptixServe.Core.Data;
+using OptixServe.Core.Models;
+
+namespace OptixServe.Core.Services;
+
+public interface IUserService
+{
+    IEnumerable<User> GetUsers();
+    User? GetUserById(string id);
+    User? GetUserByUsername(string username);
+}
+
+public class UserService(AppDbContext dbContext) : IUserService
+{
+    private readonly AppDbContext _dbContext = dbContext;
+
+    public User? GetUserById(string id)
+    {
+        return _dbContext.Users.FirstOrDefault(u => u.Id == id);
+    }
+
+    public User? GetUserByUsername(string username)
+    {
+        return _dbContext.Users.FirstOrDefault(u => u.UserName == username);
+    }
+
+    public IEnumerable<User> GetUsers()
+    {
+        return _dbContext.Users.AsEnumerable();
+    }
+}
\ No newline at end of file