Can it fix any broken file?
No. It targets common “almost JSON” mistakes. Completely truncated or binary data still fails.
jfmt.dev
JSON Repair
Paste almost-JSON — trailing commas, comments, unquoted keys — and get valid JSON back. Useful for logs, LLM output, and copy-paste from JS.
JSON formatter
Input
Output · preview.json
{ }
Run a tool to see a polished result here
What this repair pass can fix
Typical issues: trailing commas, // and /* */ comments, single-quoted strings, and unquoted keys. If the text is too far from JSON, you still get a clear error. All processing stays on this device.
Related tools
FAQ
Does repair guess missing values?
It applies conservative fixes. It will not invent business data that was never there.
Is my broken JSON uploaded?
No. Repair runs in the browser like every other JFmt tool.