Live prompt tester
A scratchpad for prompts that talks to the real models. Pick OpenAI, Anthropic, or Google, paste your own API key, write a system and user prompt, set temperature and max tokens, and send. You get the model’s actual response and its reported token usage, straight from the provider — no sign-up, no proxy, no data leaving your browser except the direct call you authorise. It is the fastest way to see how a prompt behaves before you wire it into code.
How it works
You choose a provider and model, then supply your key in a password field. The tool builds the correct request for that provider — OpenAI’s chat completions, Anthropic’s messages endpoint (with the direct-browser-access header), or Google’s Gemini generateContent — and sends it directly from your browser with your temperature and max-token settings. The response text and token counts are parsed out and shown, with loading and error states handled so a bad key or a rate limit gives you a clear message rather than a silent failure. Nothing is stored: your key and prompt live only in the page until you refresh.
Tips and notes
- Test at your shipping settings. Run the temperature and max tokens you will actually use, not the defaults — behaviour changes a lot between them.
- Use a restricted key. Since the key lives in the browser tab, prefer a scoped or low-limit key over your main production secret.
- Watch the token usage. It is your cost signal; a prompt that balloons tokens on edge cases will balloon your bill too.
- CORS is the provider’s call. If a provider blocks browser origins you will see a network error — that is expected, not a bug in the tool.