TOON Chrome Extension
Convert JSON to TOON from any tab: select text, right-click, and the TOON version is on your clipboard.
Add to Chrome (free)What it does
The extension turns structured text into TOON, a compact format for LLM prompts that uses about 43% fewer tokens than JSON on average (42.6% in the official TOON v4.1 benchmark). It is handy when you copy API responses, logs or docs examples into ChatGPT or Claude and want the smaller version.
- Right-click conversion: select text on any page and choose “Convert selection to TOON”. The result is copied to your clipboard and a toast confirms it.
- Popup converter: click the toolbar icon, paste text, and press Convert to TOON.
- Input formats: JSON, YAML, XML and CSV, detected automatically.
- Settings: indentation (2 spaces, 4 spaces or tab) and the CSV delimiter (auto, comma, semicolon, pipe or tab), saved between sessions.
- Local only: the official TOON encoder is bundled in the extension, so nothing is sent to a server.
How to use it
- Install it from the Chrome Web Store.
- Select JSON, YAML, XML or CSV text on any page.
- Right-click the selection and choose “Convert selection to TOON”.
- Paste the TOON into your prompt.
Extension, website, API or MCP?
The extension is the quickest path for small snippets you see in the browser. For bigger files, TONL, token counts and the reverse direction, use the online converter. To see the savings before you convert, try the TOON token calculator. For scripts and backends use the TOON API, and inside AI assistants use the MCP server.
FAQ
Is the TOON Chrome extension free?
Yes. It is free on the Chrome Web Store with no account.
Does the extension send my data anywhere?
No. The parsers and the TOON encoder are bundled inside the extension, and it makes no network requests to convert. Text is converted in your browser and copied to your clipboard.
Which formats can it convert?
JSON, YAML, XML and CSV. It tries them in that order and converts the first one that parses. Output is always TOON.
Can it convert TOON back to JSON?
No, the extension only encodes to TOON. Use the online converter or the MCP server's toon_to_json tool to decode.
Does it work on local files?
Yes, if you enable “Allow access to file URLs” for the extension in Chrome's extension settings.