Cloudflare released the source code for Kitesurf, its stateless browser engine built for AI agents, under the Apache 2.0 license on GitHub1. The release, announced on November 13, fulfills a commitment Cloudflare made when it first introduced Kitesurf in August.
Kitesurf runs entirely on Cloudflare Workers, parsing HTML, applying CSS, executing page JavaScript, and rendering screenshots without a browser container. Cloudflare says the engine is designed to use less CPU and memory than a full browser like Chromium while scaling on demand across its global Workers network.
Architecture and dependencies
The engine comprises three main components: the Engine, which manages browser sessions and client connections; PageScript, which runs the page and its JavaScript; and PageRenderer, which draws the result. Kitesurf supports the Chrome DevTools Protocol (CDP), allowing clients such as Puppeteer to connect.
Kitesurf is built on an ecosystem of open-source Rust packages compiled to WebAssembly. Blitz provides HTML parsing, the DOM, layout, and painting. Stylo handles CSS parsing, cascading, and computed styles. Linebender libraries supply text layout and 2D graphics, and Krilla generates PDF output. Boa runs JavaScript inside WebAssembly as a fallback when JavaScript cannot run in Dynamic Workers.
Running and deploying
Developers can run Kitesurf locally by cloning the repository, installing dependencies, and starting the engine with pnpm run dev, which launches a local development server via Wrangler. Deploying to a user's own Cloudflare account is also possible, though a Workers Paid plan is required because Kitesurf uses Dynamic Workers to create isolated Workers for each page. This self-hosted path is an alternative to using Browser Run's managed APIs.
Cloudflare added WebMCP support, new APIs, and improved compatibility in September. The company says Kitesurf is under heavy development, with ongoing work to make the engine more compatible, more reliable, and more efficient.
ANALYSIS By open-sourcing a browser engine that replaces heavyweight Chromium containers with a Workers-native stack, Cloudflare is betting that AI-agent workloads will favor lightweight, serverless browsing over traditional headless-browser infrastructure. The Apache 2.0 license and self-deploy option lower the barrier for agent developers who want to inspect or modify the rendering pipeline, while the Workers Paid requirement keeps the deployment path tied to Cloudflare's platform.