ChatGPT uses Cloudflare's Turnstile program to verify that users are running a real browser with a fully rendered and hydrated React application. The program collects 55 properties from the browser, Cloudflare network, and ChatGPT application state. The author decrypted the Turnstile bytecode and found that it uses a custom VM with 28 opcodes and randomized float register addresses. The program's purpose is to detect and prevent bot abuse of the ChatGPT API.