JSON (JavaScript Object Notation) is a lightweight data interchange format that is easy for humans to read and write, and easy for machines to parse and generate. It uses key-value pairs and arrays to represent structured data.

What does a JSON formatter do?

A JSON formatter takes raw or minified JSON and adds proper indentation and line breaks to make it human-readable. It can also validate JSON to detect syntax errors, and minify it by removing all unnecessary whitespace for smaller file sizes.

How do I validate JSON?

Paste your JSON into this tool and click Format. If the JSON contains syntax errors, the tool will display the error message with the position where the problem was detected, helping you locate and fix the issue.

What is JSON minification?

Minification removes all unnecessary whitespace (spaces, tabs, line breaks) from JSON while keeping the data identical. This reduces file size, which is useful for API responses, configuration files, and network transmission.

Is my JSON data safe?

Yes. All formatting, validation, and minification happens entirely in your browser using JavaScript. No data is sent to any server or stored anywhere.

JSON Formatter – Free Online JSON Beautifier, Validator & Minifier

What is JSON?

JSON (JavaScript Object Notation) is the most widely used data format for web APIs, configuration files, and data exchange between applications. It was derived from JavaScript but is language-independent — virtually every programming language can parse and generate JSON.

JSON Syntax Rules

JSON has a simple, strict syntax. Data is represented as key-value pairs in objects (curly braces) or ordered lists in arrays (square brackets). Keys must be strings in double quotes. Values can be strings, numbers, booleans, null, objects, or arrays.

{ "name": "Alice", "age": 28, "isStudent": false, "address": { "city": "Paris", "zip": "75001" }, "hobbies": ["reading", "cycling"] }

Common JSON Errors

The most frequent mistakes that cause JSON to be invalid include trailing commas after the last item in an object or array, using single quotes instead of double quotes for strings, unquoted keys, comments (JSON doesn't support them), and missing commas between items.

Invalid: {name: 'Alice', age: 28,}
Valid: {"name": "Alice", "age": 28}

Keys must use double quotes, strings must use double quotes, and no trailing comma.

Formatting vs. Minifying

Formatting (beautifying) adds indentation and line breaks to make JSON human-readable — essential for debugging and code review. Minifying does the opposite: it strips all whitespace to produce the smallest possible output, reducing bandwidth for API responses and file sizes for storage. Both operations preserve the data exactly — only whitespace changes.

JSON Data Types

JSON supports six data types: strings (in double quotes), numbers (integer or float, no quotes), booleans (true or false), null, objects (curly braces containing key-value pairs), and arrays (square brackets containing ordered values). Understanding these types helps you spot errors faster when validation fails.

Frequently Asked Questions

JSON (JavaScript Object Notation) is a lightweight data format used to exchange data between applications. It uses key-value pairs and arrays, and is supported by virtually every programming language.
It takes raw or minified JSON and adds proper indentation and line breaks, making it easy to read. It also validates the JSON and highlights syntax errors if any exist.
Paste your JSON and click Format. If there are syntax errors, the tool displays the error message with the position where the problem was found, so you can locate and fix it quickly.
Minification removes all whitespace — spaces, tabs, line breaks — while keeping the data identical. This reduces file size, useful for APIs, configs, and network transfer.
Yes. All processing runs in your browser using JavaScript. Nothing is sent to a server or stored anywhere. Your data never leaves your device.
JSON was designed to be a minimal data interchange format. Its creator, Douglas Crockford, intentionally excluded comments to prevent misuse as a configuration language and to keep parsers simple. If you need comments, consider JSONC or YAML instead.