Twin brothers Nithin and Nikhil from YC S24 have launched BrowserOS, an open-source, privacy-first browser that runs AI agents entirely client-side. Unlike server-based competitors like ChatGPT Atlas or Perplexity Comet, it uses local LLMs or user-provided API keys, keeping sensitive data on your machine.

The team rewrote their architecture after hitting limits with Chrome extensions. They now ship a standalone binary with Chromium and use a modified gemini-cli for the agent loop, with an adapter for the Vercel AI SDK. This local foundation enabled new filesystem access features.

Because their agent was already local, adding file read/write and shell command capabilities was straightforward. This mirrors Claude Cowork's functionality without the data privacy trade-offs. The project has grown to 8.5K GitHub stars and 100K+ downloads, now offering MCP server integration for tools like Cursor.