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Improved support for running multiple Workers with `wrangler dev`

Sep 23, 2025

Workers

You can run multiple Workers in a single dev command by passing multiple config files to wrangler dev:

wrangler dev --config ./web/wrangler.jsonc --config ./api/wrangler.jsonc

Previously, if you ran the command above and then also ran wrangler dev for a different Worker, the Workers running in separate wrangler dev sessions could not communicate with each other. This prevented you from being able to use Service Bindings ↗ and Tail Workers ↗ in local development, when running separate wrangler dev sessions.

Now, the following works as expected:

# Terminal 1: Run your application that includes both Web and API workers
wrangler dev --config ./web/wrangler.jsonc --config ./api/wrangler.jsonc

# Terminal 2: Run your auth worker separately
wrangler dev --config ./auth/wrangler.jsonc

These Workers can now communicate with each other across separate dev commands, regardless of your development setup.

./api/src/index.ts

export default {
  async fetch(request, env) {
    // This service binding call now works across dev commands
    const authorized = await env.AUTH.isAuthorized(request);

    if (!authorized) {
      return new Response('Unauthorized', { status: 401 });
    }

    return new Response('Hello from API Worker!', { status: 200 });
  },
};

Check out the Developing with multiple Workers guide to learn more about the different approaches and when to use each one.