Dynamic Workers Starter

A starter template ↗ for deploying a Worker that loads and runs Dynamic Workers.

What it does

This template demonstrates how to use the Worker Loader API to execute code at runtime. The host Worker exposes an /api/run endpoint that accepts code from the frontend, loads it into a sandboxed Dynamic Worker, and returns the result.

Use this pattern for AI agents that need to execute a snippet of code to complete an action.

Configuration

Add a worker_loaders binding to your Wrangler file:

wrangler.jsonc
wrangler.toml

{
  "worker_loaders": [
    {
      "binding": "LOADER"
    }
  ]
}

[[worker_loaders]]
binding = "LOADER"

Loading and executing a Dynamic Worker

In this example:

env.LOADER.load() creates a one-off dynamic isolate
globalOutbound: null blocks all outbound network access from the Dynamic Worker

JavaScript
TypeScript

export default {
  async fetch(request, env) {
    const { code } = await request.json();

    const worker = env.LOADER.load({
      compatibilityDate: "2026-05-01",
      mainModule: "worker.js",
      modules: {
        "worker.js": code,
      },
      // Block all outbound network access
      globalOutbound: null,
    });

    const result = await worker.getEntrypoint().fetch(request);
    return result;
  },
};

export default {
  async fetch(request, env): Promise<Response> {
    const { code } = await request.json();

    const worker = env.LOADER.load({
      compatibilityDate: "2026-05-01",
      mainModule: "worker.js",
      modules: {
        "worker.js": code,
      },
      // Block all outbound network access
      globalOutbound: null,
    });

    const result = await worker.getEntrypoint().fetch(request);
    return result;
  },
} satisfies ExportedHandler;

Running locally

npm install
npm run dev