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:

{
	"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

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