Frequently asked questions
- Is my data uploaded to a server?
- No. Every operation runs inside your browser using JavaScript. Nothing you paste or open is sent to our servers, stored or logged. You can disconnect from the network after the page loads and the tool keeps working.
- What is the largest file I can format?
- Files up to 25 MB are accepted. Documents above 5 MB switch to Large File Mode, which moves processing to a background thread and turns off the most expensive editor features so the page stays responsive.
- Does formatting change my numbers?
- No. Number literals are copied through exactly as written, so large integers, trailing zeros such as 1.0 and exponent notation such as 1e2 survive formatting unchanged.
- Why does my JSON show a trailing comma error?
- JSON does not allow a comma after the last item of an object or array, even though JavaScript does. The tool reports the exact line and column and can remove it for you.
Related tools
Stuck on an error?
Every common JSON parse error is explained separately, with the cause and the fix: common JSON errors.
How your data is handled
Everything happens on your device. There is no upload, no storage and no logging, and only your interface preferences - theme, indentation, font size and word wrap - are kept between visits. Closing the tab clears the document.