Ever experienced building something, deploy it to Vercel, just to find out that something didn't work as expected, but worked on local even with prod flags? That's why I built return0 - tired of debugging why the production environment made the code behave differently - like - why did my endpoints hang (example: node module didn't work in the production environment - silently caught error. In this case I had to modify the 3rd party node module, redeploy the code, add console.logs, took hours to figure out) - or, why was the code pointing to wrong hosts in production (reason: environment variables) - and more.

Usually to fix it you'd add logs here and there, that might surface some information. But, it's time consuming & tedious, and not the best developer experience.

return0 dynamically figures out what information to extract, like variable states. In your AI IDE - with the help of the return0 MCP server - simply explain the issue in the chat window, and it will find the root cause based on live variable states from the deployed code - like a local debugger would. And no redeployment of the code is necessary to extract more information, return0 includes an SDK that enables this dynamic tracing of your code. You also don't need to tell what information to extract.

Demo: https://www.getreturn0.com/livedemo Docs: https://www.getreturn0.com/docs