Workers Basics

Cloudflare Workers run JavaScript or TypeScript at the edge. A Worker receives a Request and returns a Response using web-standard APIs.

export default {
  async fetch(request: Request): Promise<Response> {
    const url = new URL(request.url);
    if (url.pathname === "/health") return Response.json({ ok: true });
    return new Response("Not found", { status: 404 });
  },
};

Workers are strong for lightweight APIs, redirects, request rewriting, auth gates, and edge personalization.

WARNING

Workers are not a normal long-running Node server. Check runtime APIs and limits before moving backend code directly.

Further Learning

“Cloudflare Workers fetch handler” — request/response basics
“Cloudflare Workers limits” — CPU, memory, and runtime behavior
“Wrangler Cloudflare Workers” — local dev and deploy CLI

Workers Basics

Cloudflare Workers let you run a small piece of JavaScript at Cloudflare’s edge locations worldwide — close to your users, without managing any server. It’s similar in spirit to a serverless function, but it runs even closer to visitors.

The shape of a Worker

A Worker receives a request and returns a response — that’s the whole model:

export default {
  async fetch(request) {
    const url = new URL(request.url)
    if (url.pathname === '/health') return Response.json({ ok: true })
    return new Response('Not found', { status: 404 })
  }
}

What Workers are great for

Lightweight tasks that benefit from running close to the user: quick API endpoints, redirects, rewriting requests, checking authentication before letting a request through, or personalizing content based on the visitor’s location.

What they’re NOT

WARNING

A Worker isn’t a regular, always-on server like a Node.js app. It has its own runtime with specific APIs and limits (execution time, memory). Don’t assume you can just copy-paste your existing backend code into a Worker — check what’s supported first.

In one sentence

Cloudflare Workers run small pieces of JavaScript at the edge (close to users) that receive a request and return a response — great for lightweight tasks like redirects and auth checks, but not a drop-in replacement for a full backend server.

Want to go deeper?

Switch to Expert mode above for runtime limits and the Wrangler CLI for local development.