JSON Formatter
Free online JSON formatter and validator. Format, validate, and minify JSON with real-time error detection, syntax highlighting, and one-click copy.
Features
Everything you need, nothing you don’t.
- Auto-formats as you type - no button click needed
- Detects and converts JavaScript object notation to valid JSON
- Pretty-print with 2 or 4-space indentation - switch applies instantly
- Minify JSON to remove all whitespace
- Syntax highlighting with collapsible branches in the output
- Real-time validation with exact line and column error location
- One-click copy formatted output to clipboard
- Handles large, deeply-nested JSON payloads smoothly
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Frequently asked questions
What is a JSON Formatter?
A JSON formatter (also called a JSON beautifier or pretty-printer) takes compact or unformatted JSON and adds indentation and line breaks to make it easy to read and inspect. It also validates that the JSON is syntactically correct.
Is my JSON data safe?
Yes. All data is processed entirely in your browser using JavaScript. Nothing is sent to any server. Your data stays private on your device.
What is the difference between Format and Minify?
Format adds indentation and line breaks to make JSON human-readable. Minify removes all whitespace to produce the smallest possible JSON string - useful for APIs and reducing payload sizes in production.
How do I fix an invalid JSON error?
JSON has strict syntax rules. Common mistakes include: missing double quotes around keys or string values, trailing commas after the last item in an array or object, using single quotes instead of double quotes, and including JavaScript-only values like undefined or NaN that are not valid JSON.
What does 2 spaces vs 4 spaces indentation mean?
This controls the indentation width used when formatting JSON. 2 spaces is the most common convention - used by npm, many APIs, and popular style guides. 4 spaces is common in Python and some other ecosystems. Both produce valid JSON; choose based on your team's preference.
Can I use this JSON formatter offline?
Yes. Once the page is loaded, the tool works entirely offline because all formatting logic runs in your browser. No internet connection is required to format or validate JSON.
What is JSON?
JSON (JavaScript Object Notation) is a lightweight, text-based data format. It represents data as key-value pairs, arrays, strings, numbers, booleans, and null values. JSON is the most popular format for REST APIs, configuration files, and data exchange between systems.
Does this support JavaScript object notation or JSON5?
Yes. The formatter automatically detects JavaScript object notation - including unquoted keys, single-quoted strings, and trailing commas - and converts it to valid standard JSON. JSONC (JSON with comments) is not currently supported; remove comments before pasting.
JSON Formatting Examples
What the formatter does to common JSON inputs.
Compact JSON to Formatted JSON
Paste compact, single-line JSON and the formatter adds indentation and line breaks instantly:
Input
{"name":"Alice","age":30,"roles":["admin","user"]} Formatted output (2 spaces)
{
"name": "Alice",
"age": 30,
"roles": [
"admin",
"user"
]
} String to JSON - JavaScript Object Notation
The formatter converts JavaScript object notation to valid JSON automatically. Unquoted keys, single-quoted strings, and trailing commas are handled without any manual editing:
Input (JavaScript notation)
{name: 'Alice', age: 30,} Converted to valid JSON
{
"name": "Alice",
"age": 30
}