FastAPI · React · GPT-5.6 Sol · Fly.io
PromptGym
A timed arena for AI-assisted building. You get a messy brief and a coding agent, then prompt it to ship a working app before the clock runs out, and a judge LLM grades the result and your prompting.
How It Works
Brief in. Graded build out.
BRIEF
A messy, real brief
Every challenge is a garbled meeting transcript: conflicting requirements, half-remembered thresholds, people dropping off the call. You dig out what actually has to get built.
BUILD
Prompt a coding agent
You don't write the code. You direct a GPT-5.6 Sol build agent through a three-column IDE. It writes files and runs commands in a live sandbox; a preview iframe renders the app as it takes shape.
JUDGE
A judge LLM grades you
On submit, a judge model scores the build across requirements, correctness, code quality, taste, and prompting skill, plus deterministic token-cost and speed percentiles.
Stack
FastAPI
Backend
React + Vite
Frontend
GPT-5.6 Sol
Agent + Judge
WebSockets
Live stream
subprocess sandbox
Execution
Fly.io
Deploy
The clock's already running.
Pick a challenge, out-prompt the timer, and see how the judge scores you.
Enter the arena