Free AI tools that run entirely in your browser: improve a prompt, build one from scratch, pick the right AI model, check social captions against every platform’s limits, estimate API costs, and more. No sign-up, no API key, and nothing you type is uploaded.
Why they run in your browser
Because it is faster, private and free to keep running. None of these tools call an AI model – they build, check and measure prompts using rules we publish on each tool’s page. You then take the result to the AI assistant you already use.
Questions people ask
Are the tools really free?
Yes. There is no account, no trial and no usage limit, because the tools run on your own device.
Do the tools use AI?
No. They are rule-based helpers that produce better prompts and checks for you to use in ChatGPT, Claude, Gemini or any other assistant.
Can I suggest a tool?
Please do – tell us what you need. Most new tools start as a request.