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JSON Formatter & Validator

Format, validate, and beautify JSON online. Minify or prettify JSON with syntax highlighting.

What Is a JSON Formatter?

A JSON formatter (also called a JSON beautifier or JSON prettifier) takes compact or poorly formatted JSON data and reformats it with proper indentation and line breaks, making it human-readable. It also validates the JSON structure and reports any syntax errors with precise location information.

JSON (JavaScript Object Notation) is the universal data format for web APIs, configuration files, and data storage. When working with API responses, log files, or configuration data, JSON is often minified (all whitespace removed) to reduce file size. A formatter makes this data readable for debugging and development.

Our formatter also includes a minify function - the reverse operation that removes all unnecessary whitespace to produce the smallest possible JSON string. This is useful for production deployments, reducing API payload sizes, and storing JSON in databases.

The tool shows useful statistics: total number of keys, file size in bytes, and maximum nesting depth. All processing happens in your browser - your JSON data is never sent to any server.

Common JSON Errors

Error Fix
Trailing comma Remove the last comma before } or ]
Single quotes Use double quotes for all strings and keys
Unquoted keys Wrap all keys in double quotes: "key": value
Undefined / NaN Use null instead of undefined or NaN
Comments JSON does not support comments - remove them
Missing comma Add comma between array items or object properties

Frequently Asked Questions

What is JSON?

JSON (JavaScript Object Notation) is a lightweight data-interchange format. It's easy for humans to read and write, and easy for machines to parse and generate. JSON is the de facto standard for APIs and configuration files.

How do I validate JSON?

Paste your JSON into the formatter. If it's valid, it will be formatted successfully. If there are syntax errors, the tool will highlight the exact line and character where the error occurs.

What's the difference between beautify and minify?

Beautify adds indentation and line breaks to make JSON human-readable. Minify removes all whitespace to reduce file size — useful for production APIs and reducing bandwidth.

Can I format large JSON files?

Yes. The formatter handles JSON files up to several megabytes. Very large files (over 10MB) may be slow depending on your device.

Does this tool support JSON5 or JSONC?

No, this tool validates standard JSON only. JSON5 (with comments and trailing commas) and JSONC are not supported.

Is my JSON data sent to a server?

No. All formatting and validation happens in your browser. Your data never leaves your device.

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