About JSONToonPro
70-something small tools that do one thing each and run entirely in your browser.
How it started
This site began as one tool, built to scratch one itch. When you send JSON to a model like GPT or Claude, you pay for every token, and JSON burns a lot of them repeating the same field names on every single row. We wanted a fast way to cut that waste, so we built a converter for TOON: a compact format that writes the keys once and then just lists the values underneath.
For a while, that was the entire website. One converter and a token calculator.
Then we started actually reading what people typed into Google to find us, and most of it had nothing to do with TOON. They wanted to tidy up some JSON, turn a CSV into JSON, generate a hash, work out what a hex value was in decimal. So we built those too, one page at a time, following whatever people were clearly looking for. It kept snowballing, and here we are.
What is actually here
More than 70 tools now. JSON formatting and validation, converters between JSON and CSV, XML, YAML, SQL, and TypeScript, Base64 and URL encoding, MD5 and SHA hashing, every base converter we could think of, and a growing pile of everyday utilities: a password generator, a QR code maker, a color converter, a diff checker, and more.
None of them are clever, and that is on purpose. Each one does a single job, shows you a worked example, and stays out of your way. If you want the whole list, it lives on the tools page.
Why everything runs in your browser
Every tool works locally, in the tab, using plain JavaScript. Part of that was pragmatic: we did not want to run servers or pay for them. But the bigger reason is that we did not want to be anywhere near your data. When you paste a JSON payload, an API token, or a password, it never leaves your machine.
You do not have to take our word for it. Open your browser dev tools, watch the network tab while you use any tool here, and you will see that nothing carrying your input gets sent anywhere. There is no upload, no logging, and no copy sitting on a server.
Who makes it
JSONToonPro is built by Revviz, a small software studio. We are not a big company and we are not trying to sound like one. We keep building these because we reach for them ourselves during real work, and free and local is simply the version we would want to use.
If something is broken, or there is a tool you wish existed, email support@jsontoonpro.com. A good number of the newer tools are here because someone asked for them.