sums001/Windows-Copilot-API

This open-source project reverse-engineers the Windows Copilot backend and wraps it in an OpenAI-compatible REST interface. Point your existing OpenAI SDK at localhost, swap the base URL, and you have GPT-4 and GPT-5 responses with no API key, no usage billing, and no rate-limit invoice at the end of the month. The differentiator is the drop-in compatibility: any code already talking to the OpenAI client library works without changes. That is the whole pitch, and it is a real one for prototyping and local testing. The honest reservation is that this is a reverse-engineered endpoint living on borrowed time. Microsoft can and likely will break it, rate-limit it, or require auth at any moment. Do not build a production feature on this; do use it to burn through prompt iterations before you commit real token budget. Also worth noting: depending on your jurisdiction and Microsoft's ToS, running this could be a gray area. Eyes open. -> Best for: solo founder or indie hacker prototyping before committing to paid API spend