JSON Formatter & Validator
Beautify, minify and validate JSON instantly in your browser.
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How to use it
- Paste or type your JSON into the input box — it does not need to be already valid.
- Choose the indentation style (2 spaces, 4 spaces or tab) and press Format to pretty-print, or Minify to compact it to one line.
- If the syntax is broken, the error message shows the parser position and a snippet of the surrounding text so you can fix it quickly.
- Press Ctrl+Enter (or ⌘+Enter on Mac) inside the input to format without leaving the keyboard.
About this tool
Paste raw JSON to format it with configurable indentation, or minify it to a single line. Validation runs on every operation and syntax errors are reported with position details, so broken payloads can be fixed quickly. Everything runs locally — your data never leaves the browser.
Your input never leaves the browser: this tool works entirely offline once the page has loaded.
Frequently asked questions
What is the maximum JSON size I can format?
Formatting runs entirely in your browser, so the practical limit depends on your device — inputs up to a few megabytes work fine on modern hardware. A 1 MB safety limit is applied to avoid freezing very slow devices.
Why does my JSON fail with "Unexpected token" but looks fine?
The most common causes are single quotes instead of double quotes, trailing commas after the last item, and unquoted keys. The error message shows the parser position and a snippet of the surrounding text to pinpoint the problem.
Does formatting change my data?
No. Formatting and minifying only change whitespace — keys, values and their order are preserved exactly as parsed.