How to use the JSON formatter
Paste your JSON into the editor, drop a .json file anywhere on the page, or click Upload. Line numbers appear on the left, and the status chip below the editor tells you instantly whether your JSON is valid. Then:
- Beautify — add indentation so you can read it
- Minify — strip all whitespace to save bytes
- Sort keys — arrange every object's keys alphabetically, recursively
- Copy as YAML — get the YAML equivalent for Kubernetes, Docker Compose, GitHub Actions
- Share — copies a URL containing your JSON, so you can send it to a colleague
All missing commas found at once
Most JSON validators stop at the first syntax error. This tool goes further: when the parser reports a missing comma, it scans your whole document and highlights every line that has the same problem — so you can fix them all in one pass instead of repeating the cycle eight times.
Each suspect line is highlighted in amber, and clickable line-number buttons appear in the error panel below the editor.
Why does the parser point to a different line than the one I edited?
If you delete a comma at the end of line 3, the parser doesn't know that — it only knows that when it reached the first character of line 4, it was expecting , or } and got something else. So it reports the error on line 4. That's how every JSON parser works — V8, Node, Python, Rust, Go.
This tool detects that specific case and highlights both the parser error line and the likely source line, plus every other line with the same issue.
Keyboard shortcuts
- Ctrl+Enter — Beautify
- Ctrl+M — Minify
- Ctrl+S — Download as file
- Ctrl+Shift+C — Copy result
- Ctrl+K — Clear
- Tab — Indent (inserts spaces or tab)
Works on any device, anywhere
The tool works completely offline after the first visit. It has no backend, no account requirement and no upload step. Your data never leaves your browser, which means it's safe for sensitive payloads, private API responses and confidential configuration files.
Common questions
Is this JSON formatter free?
Yes. It is free, unlimited and runs entirely in your browser.
Is my JSON uploaded anywhere?
No. All processing happens locally. Nothing is sent to any server.
Does it show all errors at once?
Yes. Missing-comma errors are detected by scanning the whole document, so every affected line is highlighted at once — not just the first one the parser trips over.
Why is the error on line 4 when I removed the comma on line 3?
The parser only reports where the unexpected token appears. This tool also finds the line that's likely missing a comma and highlights it in amber.
Can I convert JSON to YAML?
Yes. Click Copy as YAML to get the YAML representation of your JSON on the clipboard.
Can it handle large files?
It handles files up to roughly 10 MB comfortably in a browser. Larger files may slow down the page.