Bito AI is a free Chrome extension that leverages GPT-4 and ChatGPT to help developers enhance their productivity. The extension enables users to write code, understand syntax, generate test cases, explain code, comment code, check security, and explain high-level concepts. It uses OpenAI's models, eliminating the need for an OpenAI key. Bito claims to save developers up to an hour a day by providing assistance with various technical questions and tasks. The extension is currently in alpha and stores no user code, prioritizing security and privacy.