data_object Dev Tool
JSON Formatter & Validator
Paste raw or minified JSON to instantly format it with proper indentation and syntax highlighting. Validate for errors, minify for production, and copy the result. All in your browser — nothing sent to servers.
What Is JSON?
JSON (JavaScript Object Notation) is a lightweight, human-readable data interchange format. It is the dominant format for REST API responses, configuration files, and data storage. JSON represents data as key-value pairs, arrays, strings, numbers, booleans, and null — making it both machine-parseable and human-writable.
How to Use This Tool
- Format — Paste raw or minified JSON and click Format. The tool validates the input and pretty-prints it with 2-space indentation and syntax highlighting.
- Minify — Remove all whitespace and formatting for production use. Minified JSON is smaller and faster to transmit.
- Sort Keys — Alphabetically sort all object keys at every nesting level — useful for diffing and canonical serialization.
- Error highlighting — If your JSON is invalid, the tool shows the exact error message with the position of the syntax error.
- Copy — Click the Copy button to copy the formatted output to your clipboard.
JSON Syntax Rules
- Keys must be double-quoted strings:
"name"notname - Strings must use double quotes:
"value"not'value' - Trailing commas are not allowed:
[1, 2, 3,]is invalid - Comments are not allowed in standard JSON
- Numbers can be integer or float but not Infinity or NaN
- Boolean values are lowercase:
trueandfalse, notTrueorFalse
Frequently Asked Questions
Why is my JSON invalid?
Common causes: missing quotes around keys, single quotes instead of double quotes, trailing commas after the last item, comments (not allowed in standard JSON), undefined or NaN values, and unescaped special characters in strings. The error message shows the exact position.
What is minified JSON used for?
Minified JSON removes all unnecessary whitespace, reducing file size by 20–50% for typical objects. This makes API responses faster to transmit and parse. Production APIs serve minified JSON while development tools show formatted JSON.
Is my JSON data sent to a server?
No. All processing uses JavaScript's built-in JSON.parse() and JSON.stringify() functions running entirely in your browser. Your data never leaves your device.