Paste an answer from ChatGPT, Claude, Gemini — anything — and Mephistopheles checks every factual claim against independent sources, flagging or correcting what's wrong, with citations. No account needed.
Skip the copy-paste — the browser extension checks each answer right on your AI's page, while you keep using ChatGPT, Claude or Gemini. Your plan does the thinking; we fact-check it against live sources.
Get the extension →Connect your own OpenRouter key to generate and verify together, on any model. Your account pays; your key stays in this browser, never stored on our servers.
Run any model on your own account. Your key stays in this browser and is never stored on our servers.