JSON Formatter
Pretty-print, validate, or minify JSON. Everything runs locally — your data never leaves your browser.
About this tool
The JSON Formatter makes working with JSON data effortless. Paste compressed or messy JSON and instantly get a pretty-printed, syntax-highlighted version you can actually read. It also validates your JSON and pinpoints syntax errors, and can minify JSON to the smallest possible size for production use.
All processing is done client-side using the browser's native JSON.parse() and JSON.stringify() APIs. Your data never touches a server. This is particularly important when working with API responses that contain sensitive information, configuration files with keys, or proprietary data structures.
Developers use this tool daily for debugging API responses, inspecting configuration files, validating JSON before committing to a repository, and minifying payloads before deploying to production.
How to use
- Paste your JSON. Drop any JSON string into the input area — it can be minified, malformed, or already formatted.
- Choose an action. Click Format to pretty-print with syntax highlighting (choose 2 or 4 space indent), Validate to check for syntax errors with exact line numbers, or Minify to compress the JSON to a single line.
- Copy the result. Use the Copy button to copy the output to your clipboard. The character count updates automatically to show input and output sizes.
Frequently asked questions
Is my JSON data sent to a server?
No. All formatting, validation, and minification run entirely in your browser via JavaScript. Your data stays on your device at all times. You can verify this by disconnecting from the internet — the tool works fully offline after the page loads.
What JSON errors does the validator catch?
The validator catches all standard JSON syntax errors: trailing commas, missing quotes around keys, unescaped characters, single quotes (JSON requires double quotes), incomplete objects or arrays, and invalid values like undefined or NaN. The exact error position is highlighted to help you fix it quickly.
Does this support JSON5 or JSON with comments?
This tool validates against the strict JSON specification (RFC 8259). JSON5 (which allows comments, trailing commas, and unquoted keys) is not supported by the validator. If you paste JSON5, the validator will flag it as invalid. For standard JSON, it works perfectly.
Does the formatter work on mobile?
Yes. The JSON Formatter is fully responsive and works on all modern browsers including iOS Safari and Android Chrome. The text area and buttons adapt to smaller screens.