---
title: "Reverse engineer Cursor API calls | Ian Nuttall"
description: "Reverse-engineer Cursor's API calls"
canonical: "https://ian.is/post/cursor-api-reverse"
language: "en"
---

# Reverse engineer Cursor API calls

Jun 2025 / 208,204 views / [via X](https://x.com/iannuttall/status/1931117222807887875)

TensorZero reverse-engineered Cursor’s API calls to see its actual prompts and swap models under the hood

some interesting stuff in here (check first reply for the link)

\- step-by-step setup to proxy Cursor through your own gateway (they share the code)

\- cursor’s surprisingly minimal 642-token system prompts that power the whole experience

\- discovered cursor uses a “less intelligent apply model” hierarchy for code edits

\- live a/b testing between claude, gpt-4, gemini while keeping full cursor functionality

\- you can optimize cursor for your specific coding patterns vs the general population

\- technical challenges: cursor routes through their servers + electron cors issues they solved

![Image from the original X post](https://ian.is/media/tweets/1931117222807887875/1931117222807887875/dbf7f57250493cc8fcfbb7fc50d3b4830e0cbfb3a883c5dc75c1d526a92a28e5.jpg)

[https://www.tensorzero.com/blog/reverse-engineering-cursors-llm-client/](https://www.tensorzero.com/blog/reverse-engineering-cursors-llm-client/)

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