diff --git a/AuthorizationServer/AuthorizationServer.csproj b/AuthorizationServer/AuthorizationServer.csproj
index f26a38e..01a7a17 100644
--- a/AuthorizationServer/AuthorizationServer.csproj
+++ b/AuthorizationServer/AuthorizationServer.csproj
@@ -1,7 +1,9 @@
 <Project Sdk="Microsoft.NET.Sdk.Web">
 
   <PropertyGroup>
-    <TargetFramework>netcoreapp2.0</TargetFramework>
+    <TargetFramework>net8.0</TargetFramework>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <Nullable>enable</Nullable>
     <ReleaseVersion>1.0</ReleaseVersion>
   </PropertyGroup>
 
@@ -17,13 +19,13 @@
   </ItemGroup>
 
   <ItemGroup>
-    <PackageReference Include="Microsoft.AspNetCore.All" Version="2.0.9" />
-    <PackageReference Include="Microsoft.AspNetCore.Mvc.WebApiCompatShim" Version="2.0.1" />
-    <PackageReference Include="Authlete.Authlete" Version="1.4.0" />
+    <PackageReference Include="Authlete.Authlete" Version="1.5.0" />
+    <PackageReference Include="Swashbuckle.AspNetCore" Version="6.5.0" />
   </ItemGroup>
 
-  <ItemGroup>
-    <DotNetCliToolReference Include="Microsoft.VisualStudio.Web.CodeGeneration.Tools" Version="2.0.0" />
-  </ItemGroup>
+  <PropertyGroup>
+    <GenerateDocumentationFile>true</GenerateDocumentationFile>
+    <NoWarn>$(NoWarn);1591</NoWarn>
+  </PropertyGroup>
 
 </Project>
diff --git a/AuthorizationServer/Controllers/BaseController.cs b/AuthorizationServer/Controllers/BaseController.cs
index 1244330..e8e6fdc 100644
--- a/AuthorizationServer/Controllers/BaseController.cs
+++ b/AuthorizationServer/Controllers/BaseController.cs
@@ -51,8 +51,8 @@ public BaseController(IAuthleteApi api)
 
         /// <summary>
         /// Read the request body as a string.
-        /// </summary>
-        public async Task<string> ReadRequestBodyAsString()
+        /// </summary>ı
+        protected async Task<string> ReadRequestBodyAsString()
         {
             using (var reader = new StreamReader(Request.Body, Encoding.UTF8))
             {
@@ -72,7 +72,7 @@ public async Task<string> ReadRequestBodyAsString()
         /// <param name="headerName">
         /// The name of an HTTP header.
         /// </param>
-        public string GetRequestHeaderValue(string headerName)
+        protected string GetRequestHeaderValue(string headerName)
         {
             StringValues values = Request.Headers[headerName];
 
diff --git a/AuthorizationServer/Startup.cs b/AuthorizationServer/Startup.cs
index 22ba409..853e485 100644
--- a/AuthorizationServer/Startup.cs
+++ b/AuthorizationServer/Startup.cs
@@ -20,6 +20,9 @@
 using Microsoft.AspNetCore.Hosting;
 using Microsoft.Extensions.Configuration;
 using Microsoft.Extensions.DependencyInjection;
+using Microsoft.Extensions.Hosting;
+using Microsoft.OpenApi.Models;
+using System.Reflection;
 using Authlete.Api;
 using Authlete.Conf;
 
@@ -39,10 +42,22 @@ public Startup(IConfiguration configuration)
 
         public void ConfigureServices(IServiceCollection services)
         {
-            // AddWebApiConventions() is added by WebApiCompatShim.
-            // Calling the method enables Web API implementations
-            // to return an HttpResponseMessage instance directly.
-            services.AddMvc().AddWebApiConventions();
+            // AddControllers() method registers the services
+            // of Controller type to the service collection,
+            // which will be used to serve MVC-style controller
+            // endpoints in the application.
+            services.AddControllers();
+            
+            // Register the Swagger generator
+            services.AddSwaggerGen(c =>
+            {
+                c.SwaggerDoc("v1", new OpenApiInfo { Title = "Authlete Authorization Server", Version = "v1" });
+        
+                // Optional: Set the comments path for the Swagger JSON and UI.
+                var xmlFile = $"{Assembly.GetExecutingAssembly().GetName().Name}.xml";
+                var xmlPath = Path.Combine(AppContext.BaseDirectory, xmlFile);
+                c.IncludeXmlComments(xmlPath);
+            });
 
             // Register an instance of IAuthleteApi so controllers
             // can refer to it in order to call Authlete Web APIs.
@@ -57,16 +72,36 @@ public void ConfigureServices(IServiceCollection services)
         }
 
 
-        public void Configure(IApplicationBuilder app, IHostingEnvironment env)
+        public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
         {
             if (env.IsDevelopment())
             {
                 app.UseDeveloperExceptionPage();
             }
+            
+            // Enable middleware to serve generated Swagger as a JSON endpoint.
+            app.UseSwagger();
+            app.UsePathBase("/");
+
+            // Enable middleware to serve swagger-ui assets (HTML, JS, CSS, etc.)
+            app.UseSwaggerUI(c =>
+            {
+                c.SwaggerEndpoint("/swagger/v1/swagger.json", "Authlete Authorization Server API");
+                c.RoutePrefix = string.Empty; // To serve the Swagger UI at the app's root
+            });
 
             app.UseDefaultFiles();
             app.UseStaticFiles();
-            app.UseMvc();
+            
+            // Updated to use routing
+            app.UseRouting();
+
+            // Configure endpoints for controllers
+            app.UseEndpoints(endpoints => 
+            {
+                // Ensure this matches your app's routing needs
+                endpoints.MapControllers(); 
+            });
         }