Free tool · Dev Utilities
JSON Formatter / Validator
Pretty-print, minify, and validate JSON.
Paste in JSON to instantly check whether it is valid, see a clear error location if it is not, and reformat it as either neatly indented or fully minified. Validates live as you type, and a Copy or Download button is always one click away once you have a result. Useful for cleaning up API responses, config files, or debugging a malformed payload.
- Files never leave your device
- Runs entirely in your browser
- Free, no account needed
How to use JSON Formatter / Validator
Two steps, and nothing to install.
Paste your JSON
Paste or type your JSON. It validates automatically as you type, with a clear error message if something is wrong.
Copy or download the result
Choose Pretty-print or Minify, then copy the result to your clipboard or download it as a .json file.
More free tools
Free, private, and no sign-up on any of them.
How this works in your browser
This tool uses only your browser’s built-in JSON.parse and JSON.stringify, no external library at all. Validation and reformatting both happen the instant you stop typing, debounced slightly so it does not re-run on every single keystroke while pasting a large payload.
JSON Formatter / Validator vs. upload-based online tools
| Feature | JSON Formatter / Validator (in-browser) | Upload-based online tools |
|---|---|---|
| File upload required | No - never leaves your device | Yes - file is sent to a server |
| Processing queue | None - starts instantly | Often, especially at peak times |
| Watermark on output | Never | Common on free plans |
| Usage limits | None - free, unlimited use | Often capped per day or file size |
| Works offline once loaded | Yes, for most tools | No - requires a live connection |
| Account required | No | Often, for anything beyond a trial |
Who uses JSON Formatter / Validator
API developers
Pretty-print a raw API response to actually read it, or minify a config file before shipping it.
Debugging a broken payload
Paste in JSON that is failing to parse somewhere else and get a specific, readable error instead of guessing.
Anyone editing config files
Clean up hand-edited JSON before saving it, catching a stray comma or missing brace before it breaks something.
Frequently asked questions
What it can and cannot do, and what happens to your files.
Is this JSON formatter free?
Yes, completely free with no limit on how many times you use it.
What happens if my JSON is invalid?
The tool shows an error message describing what went wrong and roughly where in the text the problem is.
Can I minify JSON as well as pretty-print it?
Yes, both a readable indented format and a fully minified single-line format are available.
Does it validate automatically, or do I need to click a button?
It validates live as you type or paste, so you see a result immediately. Pretty-print and Minify are still separate buttons for choosing the output format.
Is my JSON sent anywhere?
No, formatting and validation happen entirely in your browser.
Format or validate JSON - free and instant.
Files never leave your device. No upload, no account, and free for unlimited use.