Browser Use's journey from AWS Lambda-based browser agents to a robust agent sandbox infrastructure highlights a critical architectural shift. Initially running millions of web agents on AWS Lambda, they faced challenges with memory-hungry agents impacting their REST API.

This led to a fundamental redesign: adopting Pattern 2 isolation, where the entire agent runs within a disposable sandbox. The sandbox receives only three critical environment variables (`SESSION_TOKEN`, `CONTROL_PLANE_URL`, `SESSION_ID`) and operates as a Unikraft micro-VM in production or a Docker container in development, ensuring no secrets reside within the agent process itself. Unikraft micro-VM booting in under a second provides scale-to-zero efficiency, suspending idle VMs to minimize costs while enabling instant resumption for follow-up tasks.