Development
JSON Formatter
Format, minify and validate JSON – with the exact error position and a clear explanation, repair for “almost JSON”, a tree view with paths and numbers preserved exactly.
- Runs entirely in your browser
- No data upload
- No sign-up
- Free
Input
Result
$Guide
How it works
- Paste JSON
Paste your JSON into the left field, drag a file in or open it with “Open file”.
- Let it check
The tool checks immediately. If there is an error, you see the line, column and a clear explanation – one click jumps to the spot.
- Format or minify
Choose “Formatted” with 2 or 4 spaces or a tab – or “Minified” for the most compact form. Optionally, the keys are sorted.
- Use the result
Copy the result, download it as a file or explore it in the tree view.
FAQ
Frequently asked questions
What can “Repair” do?
A lot of data is “almost JSON” – for example from JavaScript code or configuration files. “Repair” removes comments and trailing commas, replaces single with double quotes, adds quotes around keys and adds missing commas. All changes are listed.
Are large numbers changed?
No. Many formatters convert numbers internally and round large values in the process (e.g. long IDs) or turn 1.0 into 1. This formatter keeps every number exactly as it appears in the original.
What happens with duplicate keys?
Duplicate keys in the same object are formally allowed, but usually only the last value applies. The formatter keeps both and points this out.
Is my data uploaded?
No. Everything – including opening a file – happens locally in your browser. Your JSON never leaves your device.