JSON Formatter & Validator
Format, validate and minify any JSON document in your browser. Highlight syntax errors with the exact line and column, beautify nested objects with configurable indentation, and copy a clean result ready for documentation, API responses or configuration files.
How to use
- 1
Paste your JSON
Drop the JSON document into the input editor.
- 2
Choose format options
Pick indentation (2, 4 spaces or tab) and toggle key sorting.
- 3
Beautify or minify
Click Beautify for readable output or Minify for the smallest possible result.
Technical details
JSON (JavaScript Object Notation, RFC 8259) is a strict text format for structured data. Its grammar allows objects, arrays, strings, numbers, booleans and null — and nothing else. Common mistakes (trailing commas, single quotes, unquoted keys, JavaScript comments) are not legal JSON and will be rejected by the formatter with a precise error location.
The formatter parses input with `JSON.parse`, which is hardened against prototype pollution and runs in constant memory regardless of nesting depth. If parsing fails, the formatter calls a lenient parser that pinpoints the first syntax issue and suggests a fix — for example, "trailing comma after `"name"` on line 5".
Output indentation is configurable: 2 spaces (default, JavaScript convention), 4 spaces (Python convention), or tabs. Object keys can be sorted alphabetically — useful when diffing two configurations or producing canonical JSON for hashing.
Minification removes every byte of whitespace, producing the smallest possible representation suitable for HTTP transport and HTML data attributes. The minified output is byte-identical to what an optimised API would send.
Frequently asked questions
Why does my JSON fail to parse?
Can I sort keys alphabetically?
How large a document can it handle?
Is my JSON uploaded?
Does it support JSON5 or JSONC (with comments)?
This tool was tested and calibrated by our engineering team. All processing happens locally in your browser — your files and data never leave your device.