What is JSON formatting?

JSON formatting (or pretty-printing) adds consistent indentation and line breaks to a JSON string, making it easier for humans to read and debug. The data itself remains unchanged — only the whitespace is modified.

What is JSON minification?

JSON minification removes all unnecessary whitespace, line breaks, and indentation from a JSON string, reducing its file size. This is ideal for production use, API responses, and data transfer where readability is not needed.

How does this JSON validator work?

The validator uses the browser's native JSON.parse() function to check whether the input is valid JSON. If parsing fails, the error message includes the position where the syntax error was detected, helping you locate and fix the issue quickly.

What are common JSON syntax errors?

Common JSON errors include trailing commas after the last item in an array or object, using single quotes instead of double quotes, unquoted property names, missing commas between items, and including comments (JSON does not support comments).

JSON Formatter & Validator

Format, validate, and minify JSON instantly — free and private

Instant formatting | 100% client-side

Input JSON

Indent:

Output

Formatted JSON will appear here

What is JSON?

JavaScript Object Notation is the most widely used data interchange format on the web

JSON (JavaScript Object Notation) is a lightweight, text-based data format used to store and exchange structured data. Despite its name, JSON is language-independent and supported by virtually every modern programming language, database, and API. It has largely replaced XML as the standard format for web APIs and configuration files due to its simplicity and readability.

Human-Readable

JSON uses a clear key-value pair syntax with curly braces and brackets that is easy for both humans and machines to read, write, and understand at a glance.

Universal Support

Every major programming language has built-in or standard-library support for parsing and generating JSON, making it the de facto standard for REST APIs, config files, and data storage.

Lightweight

Compared to XML, JSON has minimal syntax overhead. No closing tags, no attributes, no schemas required — just clean data with significantly smaller payload sizes for the same information.

JSON Syntax Reference

A quick overview of all JSON data types and their syntax

Data Type	Description	Example
String	Text enclosed in double quotes	`"hello world"`
Number	Integer or floating-point, no quotes	`42`, `3.14`, `-17`
Boolean	Logical true or false, lowercase	`true`, `false`
Null	Represents an empty or absent value	`null`
Object	Unordered set of key-value pairs in curly braces	`{"key": "value"}`
Array	Ordered list of values in square brackets	`[1, "two", true]`

Remember: JSON keys must always be double-quoted strings. Single quotes, trailing commas, and comments are not valid in standard JSON (RFC 8259).

Frequently Asked Questions

Everything you need to know about JSON formatting and validation

JSON formatting, also known as pretty-printing, adds consistent indentation and line breaks to a compact JSON string so that it becomes easier for humans to read and debug. The underlying data is not changed — only whitespace is added. For example, {"name":"John","age":30} becomes a multi-line structure with each key-value pair on its own line.

JSON minification removes all unnecessary whitespace, indentation, and line breaks from a JSON string, producing the most compact representation possible. Use minification when transmitting data over a network (API responses, AJAX calls), storing JSON in databases, or embedding JSON in URLs — anywhere file size or bandwidth matters more than readability.

This tool uses the browser's native JSON.parse() function to validate your input. If the JSON is invalid, the parser throws a SyntaxError with a message indicating the position of the error (e.g., "Unexpected token at position 42"). This helps you quickly locate and fix syntax issues without sending data to any server.

The most frequent JSON mistakes are: trailing commas after the last item in an array or object, single quotes instead of double quotes for strings and keys, unquoted property names, missing commas between items, and comments (JSON does not support // or /* */ comments). This tool's error messages help pinpoint exactly where the issue is.

Absolutely. All processing happens entirely in your browser using JavaScript. No data is ever transmitted to any server. You can verify this by opening your browser's Developer Tools Network tab — no requests are made when you format or validate JSON. The tool works fully offline once the page has loaded.