Kitesurf is not an agent, so it is not in the directory — but it is aimed squarely at the layer underneath every browser agent listed here. It is a Rust browser runtime that runs in V8 isolates on Cloudflare Workers with no Chromium underneath, built on the observation that most of what a browser does is for a human looking at it.
The claims, from Cloudflare's own measurements: 3.1× less CPU than Chromium on screenshots and 3.8× on HTML extraction, with 4.7× and 7.0× less memory on the same two tasks. Around 215,000 Web Platform Tests pass, with hundreds more added weekly. It speaks the Chrome DevTools Protocol, so Puppeteer, Playwright and existing harnesses point at it with a parameter change rather than a rewrite. It is built on the assumption that every page load is untrusted input and every session starts fresh, with each component isolated and given access only to what it strictly needs — a direct nod to the prompt injection problem.
It is in beta and free while in beta, reached through the Browser Run API by adding browser=kitesurf. Cloudflare says it was built in about twelve weeks starting in May, and that it intends to open-source it once ready.
Worth watching for what it implies rather than what it does today. Agents that drive a browser have been paying Chromium's overhead for a workload Chromium was never designed for, and the cost of that shows up in every self-hosted deployment of Browser Use, Stagehand or Skyvern.