Our cloud browsers need to do three things at once: start quickly, remain isolated, and be cheap. That is why we rebuilt Browser Use Cloud, so a new session starts in under a second and costs $0.02 per browser hour, down from $0.06.

This is harder than it sounds. A browser has Chromium, a filesystem, cookies, cache, proxy settings, downloads, and sometimes a logged-in customer session. If one browser can read another browser's state, it creates a security problem.

The normal answer is a virtual machine, or VM. A VM is a computer inside a computer: it gets its own CPU, memory, disk, and network devices. It is separate from everything else on its host, and if the browser breaks, leaks information, or gets attacked, the damage stays within the VM.

Normal VMs, however, are too heavy for cloud browsers. We need to create them constantly, sometimes thousands at a time, and throw them away as soon as sessions end.…