What is the difference between JSON and JavaScript object syntax?

JSON is a strict subset of JavaScript object notation with specific rules: property names must be double-quoted strings, values can only be strings, numbers, booleans, null, arrays, or objects, and trailing commas are not allowed. JavaScript objects are more flexible — they allow single quotes, unquoted keys, and trailing commas. Code like {name: 'Alice'} is valid JavaScript but not valid JSON.

My JSON is from an API — why does formatting fail?

API responses are sometimes not pure JSON. Common issues: HTML error pages returned instead of JSON (check if the response starts with < instead of { or [), JSON wrapped in a callback function (JSONP format), or responses with a BOM (byte order mark) at the start. Try stripping everything before the first { or [ character.

Is there a size limit for JSON I can format?

There is no explicit limit in the tool, but very large JSON (50+ MB) may cause the browser to slow down because JSON.parse() and JSON.stringify() work in memory. For multi-megabyte JSON, consider a desktop tool like jq or VS Code's built-in JSON formatter which handles large files more efficiently.

Can this tool minify JSON (remove whitespace)?

This tool formats (beautifies) JSON. To minify JSON, use JSON.stringify(JSON.parse(input)) with no spacing argument in your browser console, or a dedicated minifier. Minifying is useful for reducing JSON payload size in production APIs.

Does JSON formatting change the data?

Formatting only adds whitespace and newlines for human readability. The data values, types, and structure are preserved exactly. Property order within objects is preserved as-is (JavaScript engines maintain insertion order for non-integer keys). Arrays maintain their original element order.

JSON Formatter — Beautify and Validate JSON Instantly

Paste minified or poorly formatted JSON and get back a properly indented, human-readable version. This tool also validates your JSON — syntax errors are shown with a clear error message rather than silently producing incorrect output. Useful for debugging API responses, reading config files, and cleaning up JSON from minifiers. Everything runs client-side with no data sent to any server.

Input

Output

How to use this tool

Paste your JSON
Paste any JSON string into the left text area — minified single-line JSON, partially formatted JSON, or a JSON object copied from a browser developer tool.
Click Convert
The formatter parses your JSON with JSON.parse() and re-serializes it with 2-space indentation via JSON.stringify(). Validation errors are shown if the input is invalid.
Copy or download
Use the Copy button to copy the formatted JSON to clipboard, or Download to save as a .json file.
Fix errors and retry
If validation fails, the error message points to the problem. Common issues: trailing commas (not valid JSON), single quotes instead of double quotes, and unquoted property names.

Frequently asked questions

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JSON Formatter — Beautify and Validate JSON Instantly

How to use this tool

Frequently asked questions

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