OpenDia is a browser extension that lets AI models control your browser automatically, leveraging existing logged-in accounts, cookies, and browser data. It uses the Model Context Protocol (MCP) to connect AI assistants like Claude, ChatGPT, and Cursor to browser automation, with specialized bypasses for sites like Twitter/X, LinkedIn, and Facebook. The tool runs locally and emphasizes privacy while allowing AI agents to interact with real user sessions for testing and automation.