How to Format and Validate JSON Online

What Is JSON?

JSON (JavaScript Object Notation) is the most widely used data format on the web. APIs, configuration files, databases, and web applications all use JSON to store and transmit structured data.

A simple JSON example:

{
  "name": "John Doe",
  "age": 30,
  "email": "[email protected]",
  "skills": ["JavaScript", "Python", "SQL"]
}

Though JSON is human-readable, real-world JSON from APIs is often minified (compressed into a single line), making it nearly impossible to read without formatting.

Step-by-Step: Format JSON Online

Step 1: Open the JSON Formatter

Go to our free JSON formatter. It processes everything in your browser — your data stays private.

Step 2: Paste Your JSON

Paste your raw or minified JSON into the input area. The tool accepts any valid JSON structure — objects, arrays, nested data, etc.

Step 3: Format or Minify

Click "Format" to pretty-print your JSON with proper indentation, or "Minify" to compress it into a single line. If your JSON has syntax errors, the tool will highlight them.

Step 4: Copy the Result

Click "Copy Result" to copy the formatted JSON to your clipboard, ready to use in your code.

Common JSON Errors and How to Fix Them

Error	Example	Fix
Trailing comma	`{"a": 1,}`	Remove the last comma
Single quotes	`{'name': 'John'}`	Use double quotes
Unquoted keys	`{name: "John"}`	Quote all keys
Missing comma	`{"a": 1 "b": 2}`	Add comma between values
Comments	`// comment`	Remove — JSON doesn't support comments

Pretty-Print vs Minified JSON

Pretty-printed JSON uses indentation and line breaks for readability. It's ideal for development, debugging, and documentation.

Minified JSON removes all whitespace. It's ideal for production, API responses, and reducing bandwidth. A minified JSON response can be 30-60% smaller than its pretty-printed version.

Our tool lets you switch between both formats with a single click.

Why Format JSON in Your Browser?

Developers often paste sensitive data into JSON formatters — API keys, user records, configuration secrets. With cloud-based formatters, this data is sent to a server.

Our JSON formatter is 100% client-side. Your JSON is parsed using the browser's native JSON.parse() and JSON.stringify() — the data never leaves your device. Read more about why this matters.