Cloudflare open-sources Kitesurf, its Workers-based browser for agents

Cloudflare has put Kitesurf on GitHub. The experimental browser engine, which it built for AI agents to run on Workers, is out under an Apache-2.0 licence, according to a 12 November 2026 changelog. You can read the source, run a copy on your own machine, or deploy an instance to a Cloudflare account.

I bet @KentonVarda wasn’t thinking about running a full browser engine on Cloudflare Workers when he created them in 2017. Kitesurf, our stateless browser for AI agents, is now open source.

November 12, 2026

Celso Martinho, who is Cloudflare’s vice president of engineering, marked the release in a post that tagged Kenton Varda. Varda created Workers in 2017. According to the repository README, Kitesurf doesn’t ship Chrome or a browser container. It still does the work of a page: it parses the HTML, applies the CSS, runs the JavaScript and takes a screenshot. And because it speaks the Chrome DevTools Protocol, a client such as Puppeteer can connect as it would to any other CDP endpoint.

The company first wrote about the project in an August blog post, describing a browser meant for agents rather than people. The pitch was that agents don’t need pixel-perfect rendering, or tabs and extensions, and that a lighter engine would use less memory and CPU. Browser Run’s documentation is also clear about the gaps. If you need video or WebGL, a bot-challenge handshake with real TLS fingerprints, or a session that stays signed in for a long time, it says Kitesurf is a poor fit, and points you at Browser Run’s default Chromium browser instead.

There’s a public playground at kitesurf.dev if you just want to see how a page comes out. The same site publishes Web Platform Tests results and Cloudflare’s own benchmarks. Browser Run’s docs put the latest WPT run at more than 235,000 passing subtests, with the strongest coverage in places agents lean on, such as the DOM and HTML. On a 14-URL corpus of Cloudflare’s own, Kitesurf used less CPU and memory than a warm Chromium pool when it took screenshots and extracted HTML, though the wall time was slower.

Running it yourself

Get the usual build tools in place, then pnpm run dev will compile the engine and start wrangler dev. It listens on localhost port 8787. Deploying to Cloudflare is a different matter. The README says you need the Workers Paid plan, because each page is isolated with Dynamic Workers. There’s no authentication built in. Leave the engine open and anyone with the URL can open DevTools, hook up a CDP client, send outbound requests from your account, and burn CPU time you pay for, which is why Cloudflare tells you to put Access or another layer in front first. The default workers.dev hostname is public, and the name follows a pattern you can guess.

What’s still early

Cloudflare still calls the project experimental, and says a lot of the remaining work is in web standards support, how faithfully it renders, and performance. A September update had already promised the source would be opened once the team felt ready to support it for the long term. Pull requests are welcome, but review time is tight. Keep changes focused, and follow the contribution guide: open an issue, get a maintainer to vouch for you, then send the PR.

Under the hood, the engine pulls in several open-source Rust projects. Blitz handles HTML, layout and painting, Servo’s Stylo does the CSS, and Boa runs the JavaScript inside WebAssembly.

kitesurf is now open source

what are you going to build with it?

November 12, 2026