Reverse Engineering Cursor's LLM ClientJune 5, 2025 · Viraj Mehta, Aaron Hill, Gabriel BianconiWhat happens under the hood at Cursor? TensorZero is an open-source framework that helps engineers optimize LLM applications with downstream feedback signals (e.g. TensorZero exposes an OpenAI-compatible inference endpoint, so we can easily configure Cursor to call TensorZero instead of OpenAI. In the end, the workflow looked like this: Cursor → Ngrok → Nginx (self-hosted) → TensorZero (self-hosted) → LLM providersBut it didn’t work. This blog post demonstrates how we successfully reverse-engineered Cursor’s LLM client by setting up TensorZero as a self-hosted proxy service, enabling us to observe, analyze, and experiment with different LLM models while maintaining the full Cursor experience.