The best way to do MCP auth just got better: Workers OAuth Provider goes v1, with a new split API and full support for MCP 2026-07-28

@cloudflare/workers-oauth-provider is now v1, with a new split API. One Worker acts as the authorization server: it signs users in and issues tokens. Your MCP server acts as the resource server, and can run in another Worker. It validates each token with the authorization server over a Service Binding, without crossing the public Internet.

• It supports the MCP 2026-07-28 authorization specification, including Client ID Metadata Documents and issuer identification. It still works with older clients, including those using Dynamic Client Registration.
• insufficientScope() gives you step-up authorization in one line.
• The authorization server and the resource server can run in different Workers with different WAF and rate limiting rules.
• One authorization server can issue tokens for many MCP servers.
• A migration skill ships in the npm package so a coding agent can perform the upgrade.

The split API

import { OAuthAuthorizationServer, OAuthResourceServer, insufficientScope, } from "@cloudflare/workers-oauth-provider"; import { WorkerEntrypoint } from "cloudflare:workers"; // auth-server Worker: signs users in and issues tokens for both MCP servers. const authorizationServer = new OAuthAuthorizationServer({ issuer: "https://auth.example.com", resources: [ "https://calendar.example.com/mcp", "https://drive.example.com/mcp", ], scopesSupported: ["calendar:read", "calendar:write", "offline_access"], clientIdMetadataDocumentEnabled: true, }); export class AuthServer extends WorkerEntrypoint { fetch(request) { if (new URL(request.url).pathname === "/authorize") { return showConsent(request, this.env); } return authorizationServer.fetch(request, this.env, this.ctx); } validateToken(resource, token) { return authorizationServer.validateToken(resource, token, this.env); } } // calendar MCP Worker: checks tokens with AuthServer over a Service Binding. export const calendar = new OAuthResourceServer({ resourceMetadata: { resource: "https://calendar.example.com/mcp", authorization_servers: ["https://auth.example.com"], }, requiredScopes: ["calendar:read"], validateToken: (env) => env.AUTH_SERVER.validateToken, handler: { fetch(request, env, ctx) { if ( request.method === "POST" && !ctx.auth.scope.includes("calendar:write") ) { return insufficientScope(ctx.auth, ["calendar:read", "calendar:write"]); } return handleMcp(request, ctx.props); }, }, });

import { OAuthAuthorizationServer, OAuthResourceServer, insufficientScope, } from "@cloudflare/workers-oauth-provider"; import { WorkerEntrypoint } from "cloudflare:workers"; // auth-server Worker: signs users in and issues tokens for both MCP servers. const authorizationServer = new OAuthAuthorizationServer<Env>({ issuer: "https://auth.example.com", resources: [ "https://calendar.example.com/mcp", "https://drive.example.com/mcp", ], scopesSupported: ["calendar:read", "calendar:write", "offline_access"], clientIdMetadataDocumentEnabled: true, }); export class AuthServer extends WorkerEntrypoint<Env> { fetch(request: Request) { if (new URL(request.url).pathname === "/authorize") { return showConsent(request, this.env); } return authorizationServer.fetch(request, this.env, this.ctx); } validateToken(resource: string, token: string) { return authorizationServer.validateToken(resource, token, this.env); } } // calendar MCP Worker: checks tokens with AuthServer over a Service Binding. export const calendar = new OAuthResourceServer<Env, AuthProps>({ resourceMetadata: { resource: "https://calendar.example.com/mcp", authorization_servers: ["https://auth.example.com"], }, requiredScopes: ["calendar:read"], validateToken: (env) => env.AUTH_SERVER.validateToken, handler: { fetch(request, env, ctx) { if ( request.method === "POST" && !ctx.auth.scope.includes("calendar:write") ) { return insufficientScope(ctx.auth, ["calendar:read", "calendar:write"]); } return handleMcp(request, ctx.props); }, }, });

In the example, env.AUTH_SERVER.validateToken is that Service Binding call. The calendar Worker needs no KV namespace of its own.

{ "name": "calendar-mcp", "main": "src/index.ts", // Set this to today's date "compatibility_date": "2026-10-14", "services": [ { "binding": "AUTH_SERVER", "service": "auth-server", "entrypoint": "AuthServer", }, ], }

name = "calendar-mcp" main = "src/index.ts" # Set this to today's date compatibility_date = "2026-10-14" [[services]] binding = "AUTH_SERVER" service = "auth-server" entrypoint = "AuthServer"

OAuthResourceServer publishes the RFC 9728 protected resource metadata that MCP clients use to find your authorization server. It answers requests without a token with a 401 challenge that points to that metadata. It also rejects tokens issued for any other resource.

You can still use OAuthProvider as both the authorization server and the MCP server. For most 0.x deployments, the only required change is to add resourceMetadata: { resource }.

Other updates and helpers

• Consent page and upstream sign-in helpers implement the MCP confused deputy protections.
• Sliding refresh token expiry with refreshTokenIdleTTL.
• Resumable KV cleanup with purgeExpiredData().
• An internal reason on every error passed to onError.

Upgrade with the migration skill