I built a thing that runs the same prompt through GPT, Claude and Gemini at the same time and shows where they agree and disagree. A few founder friends have been using it to stress test ideas before pitching anyone.

One called it "depressing but strangely addicting" which honestly might be the best review we've gotten. Sometimes all three agree your idea has problems and that sucks. But better to hear it from three AIs at 2am than a VC who ghosts you.

The interesting part is when they dont agree. One says the market is too small, another says its the only thing worth building. Thats the signal that the answer actually matters.

Had to test it on a dumb question too so I asked which model is the weakest. They each picked a different one. GPT called itself the weakest. Claude said Gemini. Gemini said Claude but used outdated data from 2024 so it lost the argument by not doing its homework.

Its called Serno, the feature is Council Mode. 

Free to try: [serno.ai](https://serno.ai/?utm_source=reddit&utm_medium=social&utm_campaign=sideproject) you can use council mode without logging in with the top models so go nuts

I made GPT, Claude and Gemini evaluate the same startup idea at once. A founder friend called it depressing but strangely addicting.