JSON Formatter & Validator
Formats, validates and minifies JSON in real time, with clear syntax-error diagnostics.
Mode
Indentation
What is JSON
JSON (JavaScript Object Notation) is a lightweight text format for representing structured data — key-value pairs, lists and nested values. It's the most widely used format today for exchanging data between applications, especially in web APIs, configuration files and document storage.
What a JSON Formatter is for
A JSON Formatter organizes a minified or messy JSON into a readable, indented version that's easy to review — and, at the same time, validates whether the text actually follows JSON syntax rules, pointing out exactly where it doesn't.
Pretty Print
Pretty Print is the readable formatting: every key, value and nesting level on its own line, with consistent indentation (2 or 4 spaces). It's the ideal form for reading, reviewing and debugging a JSON by hand.
Minify
Minify strips all unnecessary whitespace and line breaks, shrinking the JSON to its smallest possible size without changing the data itself. It's the ideal form for transmitting or storing JSON, where every byte counts and human readability isn't the goal.
Validation
A JSON is only considered valid if it strictly follows the specification — keys always in double quotes, no trailing comma before closing an object or array, no comments. This tool validates using your browser's own native engine, and points to the line and column of the error whenever the browser reports that position.
Frequently asked questions
No. All processing happens in your browser — the JSON you paste here never travels over the internet and is never logged anywhere.
Format (Pretty Print) arranges the JSON across multiple indented lines, for human reading. Minify removes all extra whitespace, for the smallest possible size — the same data, two representations.
The most common causes are a trailing comma before "}" or "]", using single quotes instead of double quotes, and object keys without quotes. When the browser reports the error position, the tool points to the line, column and, when possible, the likely cause.
File upload accepts up to 5 MB. Pasting directly into the text field has no technical limit, but very large files may slow the browser down.