Cloudflare opens Kitesurf for local AI browser testing

Cloudflare has released the source code for Kitesurf, its browser engine for AI agents, under the Apache 2.0 license. The company listed the change in its developer changelog on November 12 and described the code, local build and deployment options in a November 13 blog post. Developers can now build the engine on their own computers and inspect or change how it handles the pages their agents use.

Kitesurf renders web pages so an agent can read or interact with them. Cloudflare introduced it as a service in August. A September update expanded support for web standards and added capabilities including WebMCP, which lets participating sites present tools to an AI agent. The public repository adds a way to investigate behavior on the engine side. A developer who sees a missing element on an internal page can examine the code that produced the result, as well as the page itself.

What the engine renders

The engine reads HTML, applies styling and runs the scripts that populate a page. A business site might, for example, load a list of orders after its initial page appears. The agent needs the resulting page to see those orders. Kitesurf does this processing in Cloudflare’s Workers environment without opening a full browser window. Cloudflare describes using a separate execution environment for each page.

Tools such as Puppeteer can connect over the Chrome DevTools Protocol, a common interface for asking a browser to navigate or capture a page. The repository says some features from Chrome’s developer tools are still missing. For an existing automation, compatibility depends on the commands it uses and the features the site needs.

Less memory, longer waits in Cloudflare’s tests

Cloudflare’s Browser Run documentation compares Kitesurf and Chromium across 14 URLs. The table reports medians from five runs of the service’s Quick Actions and uses an already warm pool of Chromium instances. For screenshots, Kitesurf used 57.8 MiB of memory and 380 milliseconds of CPU time. Chromium used 271.0 MiB and 1,173 milliseconds of CPU time. From the start of the request to the result, Kitesurf took 1,148 milliseconds and Chromium took 637 milliseconds.

The HTML extraction test showed a similar pattern. Kitesurf used 39.4 MiB of memory and took 820 milliseconds of elapsed time. Chromium used 273.7 MiB and took 472 milliseconds. CPU time measures time spent computing, while elapsed time registers how long an application waits for the result. Cloudflare’s figures apply to the sites and configurations in its test. The delay and resource use of a production workflow depend on its pages and how it runs.

The repository describes local development with Wrangler and a first build that compiles parts of the engine. Developers can then deploy their copy to their own Cloudflare account. Hosting it there requires a Workers Paid plan because the per-page execution environments rely on Dynamic Workers. Cloudflare lists its managed Kitesurf beta separately as free within per-account limits.

Cloudflare also reports more than 235,000 passes on Web Platform Tests, a suite of small checks for browser standards. Its published snapshot lists 97 percent for the document object model and 83 percent for URLs. Those checks measure individual browser features. A workflow that combines sign-in, rendering and multiple requests still depends on how the target site uses them.

Kitesurf’s documented uses include one-off tasks such as extracting page content and producing screenshots or PDFs from compatible sites. Cloudflare lists video playback, WebGL graphics and long authenticated sessions that need to retain state among the features the engine cannot yet handle. Browser Run offers Chromium as its default engine for workloads that need those capabilities.