vctrl/ktor-oauth-mcp-sample

ktor-oauth-mcp-sample

A production-ready OAuth-protected MCP server for Claude and other MCP clients.

Built with ktor-server-mcp and ktor-server-oauth.

Works with Claude

This is a remote MCP server (HTTP/SSE transport, not stdio). It works out of the box with any MCP client that supports network-based servers:

• Open registration - clients register automatically via OAuth 2.0 Dynamic Client Registration (public clients with PKCE)
• Reverse proxy ready - designed to work behind nginx, Caddy, Traefik, etc. without modification

Adding to Claude

Once deployed with HTTPS (e.g., at https://mcp.example.com), add these connectors:

Claude Desktop / Web / Mobile (Pro, Max, Team, Enterprise):

1. Go to Settings → Integrations
2. Click "+ Add Custom Connector"
3. Add each endpoint:
   • Name: Contact Sample → URL: https://mcp.example.com/contact
   • Name: Mom's Name Sample → URL: https://mcp.example.com/mom
4. OAuth login prompts automatically on first use

Claude Code CLI:

claude mcp add --transport http contact https://mcp.example.com/contact
claude mcp add --transport http mom https://mcp.example.com/mom

Then use /mcp inside Claude Code to authenticate.

SSL Required

MCP clients like Claude require HTTPS. Options:

1. Reverse proxy (recommended) - terminate SSL at nginx/Caddy/Traefik, proxy to this server on HTTP
2. Ktor SSL - configure directly in application.conf:

   ktor {
       deployment {
           sslPort = 8443
           ssl {
               keyStore = /path/to/keystore.jks
               keyAlias = mykey
               keyStorePassword = changeit
               privateKeyPassword = changeit
           }
       }
   }
   

Quick Start

Both options start the server at http://localhost:8080 and work identically behind a reverse proxy with SSL for production use with Claude.

Gradle

./gradlew run

Docker

docker compose -f deployment/docker-compose.yml up

See for more deployment options.

Features

• OAuth 2.0 with dynamic client registration (RFC 7591)
• Provision flow for collecting user credentials during auth
• Session-bound storage tied to OAuth tokens
• MCP tools with access to user session data

How It Works

1. MCP client connects and triggers OAuth flow
2. User completes the provision form (e.g., enters their name/contact info)
3. Data is stored in a session bound to the OAuth token (or as encrypted JWT claims)
4. MCP tools access session data via call.sessions.get<T>() or JWT claims

Included Examples

This sample includes two MCP endpoints demonstrating different patterns:

/contact - Session Storage

Uses bearer-bound sessions to store contact information.

Tools:

• greet_me - Returns a personalized greeting
• my_contact_info - Returns stored contact info (text or JSON)
• update_contact - Update email, phone, or company
• send_test_email - Simulates sending email to stored address

/mom - Encrypted JWT Claims

Stores data as encrypted claims in the JWT token itself.

Tools:

• your_moms_name - Returns the name stored in encrypted JWT claim

Customization

• Edit Application.kt to add your own tools and endpoints
• Modify templates in src/main/resources/templates/ for provision forms
• Choose between session storage or encrypted JWT claims based on your needs

Project Structure

src/main/kotlin/com/example/
└── Application.kt           # Server, routes, and tools

src/main/resources/templates/
├── provision.html           # Contact info provision form
└── mom-provision.html       # Mom's name provision form

License

Apache 2.0