Is my JSON data uploaded to a server?

No. All formatting and validation runs locally in your browser using JavaScript. Your data never leaves your device.

What indentation options are available?

You can choose between 2-space and 4-space indentation for the formatted output.

How does JSON validation work?

The tool uses the browser's built-in JSON.parse(). If your JSON is invalid, it shows the error message with the approximate line and column number.

What is JSON minification?

Minification removes all whitespace (spaces, newlines, tabs) from valid JSON to produce the most compact representation, useful for APIs and storage.

JSON Formatter & Validator — Free Online JSON Beautifier

What is a JSON Formatter?

A JSON Formatter (also called a JSON Beautifier or JSON Prettifier) takes compact or messy JSON and reformats it with consistent indentation so it’s easy to read. This tool formats, validates and minifies JSON directly in your browser — no data is ever uploaded to a server.

How to Use

Paste your JSON into the input box on the left
Click Format (2 spaces) or Format (4 spaces) to prettify
Click Minify to produce compact, whitespace-free JSON
Click Copy to copy the output to your clipboard

The validator runs automatically as you type, showing a green ✓ for valid JSON or a red ✗ with the error position for invalid input.

JSON Format Rules

Valid JSON must follow these rules:

Keys must be strings wrapped in double quotes: "name", not name
Values can be strings, numbers, booleans (true/false), null, arrays or objects
No trailing commas — {"a":1,} is invalid
No comments — JSON does not support // or /* */ comments
Strings use double quotes — single quotes are not valid JSON

Common JSON Errors

Error	Example	Fix
Missing quote on key	`{name: "Alice"}`	`{"name": "Alice"}`
Trailing comma	`[1, 2, 3,]`	`[1, 2, 3]`
Single quotes	`{'key': 'value'}`	`{"key": "value"}`
Undefined value	`{"x": undefined}`	Remove or use `null`
Comments	`{"a":1 // comment}`	Remove comments

When to Use Minification

Minified JSON removes all spaces, tabs and newlines to produce the most compact representation. Use it when:

Sending JSON over an API to reduce payload size
Storing JSON in a database or config file to save space
Embedding JSON in a URL or HTML attribute

JSON vs JavaScript Object Literals

JSON looks similar to JavaScript objects but has stricter rules. A JavaScript object allows unquoted keys, single quotes and trailing commas — none of which are allowed in JSON. When copying a JavaScript object to use as JSON, you must:

Wrap all keys in double quotes
Replace single-quoted strings with double-quoted strings
Remove trailing commas
Replace undefined values with null or omit the key

Formatting Large JSON Files

If your JSON is very large, the formatter may take a moment. For files over 1 MB, consider using a command-line tool like jq:

cat data.json | jq .

For small and medium JSON (under ~500 KB), this browser-based tool is fast and convenient.

Privacy

All processing happens in your browser using JavaScript’s built-in JSON.parse() and JSON.stringify(). Your JSON is never sent to any server, stored, or logged. You can even use this tool offline once the page has loaded.

JSON Formatter