JSON Formatter & Validator
Beautify, minify, and validate JSON instantly. Precise error messages with line and column numbers — works fully in your browser.
JSON input
Output
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What this JSON formatter does
This tool parses your JSON using the browser's strict JSON.parse and lets you format the result three ways:
- Beautify — pretty-prints the JSON with your chosen indent (2 spaces, 4 spaces, or tab). Use when a response arrives as one giant line and you need to read it.
- Minify — strips every whitespace character outside string literals, producing the most compact valid JSON. Saves bytes when embedding JSON in URLs, attributes, or config files.
- Validate — just parses the input. If it succeeds you get a green "Valid JSON"; if not, you get the error line and column.
Optionally you can sort all object keys alphabetically — useful for diffing two JSON payloads or producing deterministic output.
How to use
- Paste JSON into the left panel or upload a
.jsonfile. - Pick indent size and whether to sort keys.
- Click Beautify, Minify, or Validate.
- If there's a syntax error, the status line shows where it is. Fix it in the input and re-run.
Common JSON mistakes this will catch
- Trailing commas —
{"a": 1,}is invalid JSON (use JSON5 if you need them). - Single quotes — JSON strings must use
"double quotes". - Unquoted keys —
{ key: 1 }is JavaScript, not JSON. - Comments — JSON does not support
//or/* */. - Unescaped control characters inside strings.
- Truncated or unterminated strings.
Privacy
Your JSON never leaves the page. Parsing and formatting happen using the browser's native engine; you can disconnect from the internet and this tool will still work.