JSON Formatter & Validator
Free JSON formatter and validator: beautify, minify, sort keys and find syntax errors instantly. Upload a file or paste. Runs locally in your browser.
FreeRuns in your browserNo sign-up
Options
Your JSON never leaves your browser.
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How to use the JSON Formatter & Validator
- Paste JSON or upload a .json file.
- Click Beautify to indent or Minify to compress.
- Fix any error message shown, then copy or download.
What is JSON?
JSON (JavaScript Object Notation) is the standard text format for data exchange between web apps and APIs. It uses objects {}, arrays [], strings, numbers, booleans and null.
What this tool does
- Beautify adds indentation and line breaks so humans can read it.
- Minify removes all extra whitespace to save bytes.
- Validate tells you when the syntax is wrong.
- Sort keys orders object keys alphabetically for easy comparison.
Most common JSON errors
- Trailing commas after the last item.
- Single quotes instead of double quotes.
- Unquoted keys such as
{name: "A"}. - Comments, which JSON does not allow.
Because parsing runs in your browser, private API responses and tokens stay on your device.
Frequently asked questions
How do I format JSON online?
Paste it into the input box and click Beautify.
Why does my JSON say invalid?
Usually a trailing comma, single quotes, an unquoted key or a comment. The message shows the position.
Is my JSON uploaded?
No. It is parsed locally in your browser.
Can it handle large files?
Yes, up to what your browser memory allows. Several megabytes work fine.