JSON Formatter & Validator
If you have ever received a long block of JSON that looks like one big wall of text, this tool makes it readable in one click. Paste your raw or minified JSON below and click Format to see it with proper indentation and line breaks. The tool also checks your JSON for errors and tells you exactly where a problem is if it finds one. Developers use this when working with API responses, config files, or data exports. You can also use it to minify JSON by removing all the extra spaces.
Frequently Asked Questions
What is JSON?
JSON stands for JavaScript Object Notation. It is a lightweight text format used to store and transfer data between applications. It is commonly used by websites and apps to send data between a server and a browser, and is easy for both humans and computers to read.
Why is my JSON invalid?
Common causes include missing quotes around key names, trailing commas after the last item in an array or object, using single quotes instead of double quotes, and missing or extra curly braces or square brackets. This tool tells you the exact location of the error.
What is JSON minification?
Minification removes all unnecessary whitespace and line breaks to make the JSON as small as possible. This is useful when sending data over a network because smaller files transfer faster. Use the Minify button to compress your JSON in one click.
What is the difference between JSON and XML?
Both are formats for storing structured data. JSON is shorter, easier to read, and faster to parse, which is why most modern APIs use it. XML uses opening and closing tags similar to HTML, while JSON uses curly braces and square brackets.
What data types does JSON support?
JSON supports six types: string (double quotes only), number (integer or decimal), boolean (true or false), null, object (key-value pairs in curly braces), and array (ordered values in square brackets). JSON does not support comments, single-quoted strings, or trailing commas after the last item — these are the most common causes of invalid JSON errors.
How do I fix a trailing comma error in JSON?
A trailing comma appears after the last item in an object or array: {"key": "value",} is invalid. Remove the comma after the last item. Most JSON linters and formatters will highlight the exact line. If you are generating JSON programmatically, use your language's built-in JSON serializer rather than string concatenation to avoid this mistake.
Can JSON store binary data like images?
Not natively. JSON only supports text-based values. To include binary data, encode it as Base64 first, then include the string. This is common in APIs that transfer small images inline as data URIs (data:image/png;base64,...). For large files, link to a URL rather than embedding the data — Base64 increases file size by 33%.
How It Works
The tool parses your input using JSON.parse() — the browser's native JSON parser. If parsing succeeds, it re-serializes the object with JSON.stringify(obj, null, 2) for pretty-printing (2-space indent) or JSON.stringify(obj) for minification. Validation errors are reported with the character position of the first syntax problem.
Common JSON Errors
The most frequent JSON errors are: trailing commas after the last item in an object or array, single-quoted strings (must be double quotes), unquoted property keys, comments (// or /* */ are not valid in JSON), and missing commas between items. Paste the broken JSON here to pinpoint which line has the error.
JSON vs JSON5
JSON5 is a superset of JSON that allows comments, trailing commas, single quotes, and unquoted keys — the things developers wish standard JSON supported. It is used in config files (like .eslintrc) but not in APIs. If your JSON-like file has comments in it, it is likely JSON5 or JSONC (JSON with Comments) format, not standard JSON.
When to Use This
Use to beautify a minified API response so you can read its structure, to validate JSON before sending it to an API, to minify a config file before deploying, or to find the syntax error in a broken JSON string that a server or linter is rejecting.
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