@dotdo/oauth

OAuth 2.1 authorization server for MCP (Model Context Protocol) compatibility.

The Problem

You're building an MCP server. Claude and ChatGPT need to authenticate. But OAuth 2.1 is new, the docs are scattered, and you've spent hours debugging .well-known endpoints and CORS headers.

The Solution

import { createOAuth21Server, MemoryOAuthStorage } from '@dotdo/oauth'

const oauth = createOAuth21Server({
  issuer: 'https://your-mcp.do',
  storage: new MemoryOAuthStorage(),
  upstream: {
    provider: 'workos',
    apiKey: process.env.WORKOS_API_KEY,
    clientId: process.env.WORKOS_CLIENT_ID,
  },
})

// Mount it. Done.
app.route('/', oauth)

Your MCP server now speaks OAuth 2.1. Claude can connect.

What This Does

This package creates a federated OAuth 2.1 server:

• It's an OAuth SERVER to MCP clients (Claude, ChatGPT)
• It's an OAuth CLIENT to your identity provider (WorkOS, Auth0)

┌─────────────────┐      ┌──────────────────┐      ┌─────────────┐
│  Claude/ChatGPT │ ───> │  Your MCP Server │ ───> │   WorkOS    │
│  (OAuth Client) │      │ (OAuth Server +  │      │  (Upstream) │
│                 │ <─── │   OAuth Client)  │ <─── │             │
└─────────────────┘      └──────────────────┘      └─────────────┘

Endpoints

Once mounted, your server provides:

Features

• OAuth 2.1 compliant - PKCE required, S256 only
• MCP compatible - Works with Claude, ChatGPT, and other MCP clients
• Federated auth - Delegates to WorkOS, Auth0, or custom providers
• Storage agnostic - Bring your own storage backend
• Zero dependencies on oauth.do or @dotdo/do - this is the leaf package

Storage

The package provides MemoryOAuthStorage for testing. For production, implement the OAuthStorage interface:

import type { OAuthStorage } from '@dotdo/oauth'

class MyStorage implements OAuthStorage {
  async getUser(id: string) { /* ... */ }
  async saveUser(user: OAuthUser) { /* ... */ }
  async getClient(clientId: string) { /* ... */ }
  // ... other methods
}

If you're using @dotdo/do, it provides DOAuthStorage that implements this interface using Durable Object SQLite storage.

Configuration

createOAuth21Server({
  // Required
  issuer: 'https://your-domain.com',      // Your server's URL
  storage: new MemoryOAuthStorage(),       // Storage backend
  upstream: {                              // Identity provider
    provider: 'workos',
    apiKey: 'sk_...',
    clientId: 'client_...',
  },

  // Optional
  scopes: ['openid', 'profile', 'email'],  // Supported scopes
  accessTokenTtl: 3600,                    // 1 hour (default)
  refreshTokenTtl: 2592000,                // 30 days (default)
  authCodeTtl: 600,                        // 10 minutes (default)
  enableDynamicRegistration: true,         // Allow client registration
  debug: false,                            // Debug logging

  // Callbacks
  onUserAuthenticated: async (user) => {
    console.log('User logged in:', user.email)
  },
})

Upstream Providers

WorkOS

upstream: {
  provider: 'workos',
  apiKey: process.env.WORKOS_API_KEY,
  clientId: process.env.WORKOS_CLIENT_ID,
}

Custom Provider

upstream: {
  provider: 'custom',
  apiKey: 'your-client-secret',
  clientId: 'your-client-id',
  authorizationEndpoint: 'https://auth.example.com/authorize',
  tokenEndpoint: 'https://auth.example.com/token',
}

PKCE Utilities

The package also exports PKCE utilities:

import { generatePkce, verifyCodeChallenge } from '@dotdo/oauth/pkce'

// Generate PKCE pair
const { verifier, challenge } = await generatePkce()

// Verify during token exchange
const valid = await verifyCodeChallenge(verifier, challenge, 'S256')

Architecture

This package is the leaf in the dependency chain:

@dotdo/oauth (this package - pure OAuth 2.1, storage interface)
     ↓
@dotdo/do (depends on @dotdo/oauth, implements DOAuthStorage)
     ↓
oauth.do (depends on @dotdo/do for storage)
     ↓
dotdo (depends on oauth.do for auth)

Each layer adds capabilities:

• @dotdo/oauth - OAuth 2.1 primitives, abstract storage interface
• @dotdo/do - Concrete storage using Durable Object SQLite
• oauth.do - High-level auth SDK with session management
• dotdo - Full framework with auth built-in

License

MIT