10 / json-formatter
free online tool
JSON Formatter
Format, validate, and minify JSON instantly in your browser.
Formatted JSON will appear here...
how to use
- 01
Paste your JSON into the input panel.
- 02
Click 'Format' to pretty-print, or 'Minify' to compact it.
- 03
Use 'Copy' to copy the output to your clipboard.
about
What is this tool?
JSON Formatter validates and pretty-prints JSON data using JavaScript's JSON.parse and JSON.stringify. It helps developers quickly inspect API responses, debug configuration files, and reduce payload size by minifying. Invalid JSON is flagged with a clear error message.
why use this tool
- -Instantly readable JSON with proper indentation.
- -Validates JSON and shows the exact error for invalid input.
- -Minify to reduce payload size for production.
- -All processing is local — paste API keys safely.
features
- -Pretty-print with 2 or 4-space indentation.
- -Minify for compact JSON output.
- -Syntax error detection with clear messages.
- -Copy formatted or minified JSON with one click.
comparison
Formatted vs Minified JSON
| Mode | Readability | File Size | Use Case |
|---|---|---|---|
| Pretty (2 spaces) | High | Largest | Development, debugging |
| Pretty (4 spaces) | Highest | Largest+ | Documentation |
| Minified | Low | Smallest | API payloads, production |
All processing happens entirely in your browser using JavaScript. No files, text, or data are ever sent to a server. Your data stays on your device.
✦ tip from dragontail
When debugging API responses in Dragontail's backend, I paste raw JSON directly into this formatter before doing anything else. Minified JSON from a real API response is nearly impossible to read at a glance — formatting it first saves 10× the debugging time. I keep this tool open in a pinned tab whenever I'm doing API work.
faq
Is my JSON data sent to a server?
No. JSON.parse and JSON.stringify run entirely in your browser. Nothing is transmitted.
What happens with invalid JSON?
The tool displays the browser's native parse error message so you can quickly locate the issue.
Can I format very large JSON?
Yes, but very large JSON objects (>10 MB) may be slow depending on your device. For very large files, a desktop tool may be faster.