JSON Formatter - Format, Validate & Beautify JSON Online

Input

Output

What is JSON Formatter?

Got messy, minified JSON that's impossible to read? This tool fixes that. It takes your JSON (JavaScript Object Notation) and makes it beautiful - proper indentation, line breaks, everything organized. Whether you're debugging API responses, checking config files, or just trying to understand what your JSON actually says, this makes it readable.

JSON is what most web APIs speak, and MDN's JSON reference is a good place to look up how JavaScript reads and writes it. The formatter parses your input under the RFC 8259 JSON specification and re-prints it with 2-space indentation, so anything it formats is valid JSON. Big integers such as 19-digit IDs keep every digit. And if you paste a JSON document that was itself stored as a quoted, escaped string (common in logs), it's unwrapped and formatted as the document inside.

Best part? Everything happens instantly in your browser. No server uploads, no data storage - just paste, format, and copy. Your JSON stays private. For a quick second opinion, you can also run your output through another online JSON formatter.

How to Use the JSON Formatter

Follow these steps to format and beautify your JSON. Each step uses the actual buttons and panels on this page.

Paste, Upload, or Load Sample

Paste minified JSON into the left Input panel, or click Upload to load a .json or .txt file. Click Sample to see example minified JSON. Example of what minified input looks like:

{"subscriberId":"SUB-1001","plan":"Unlimited 5G","dataUsage":45.2,"status":"active"}

Invalid JSON shows "Invalid JSON:" followed by the parser's message, which usually includes the position or line. Fix that spot, and the output updates.

View Formatted Output

The right Output panel updates as you type. Nested objects get 2-space indentation and arrays are spread over lines. The formatter validates your JSON per RFC 8259: if it's valid, it formats; if not, you see the error.

Copy, Download, or Minify

Click Copy to copy the formatted JSON to your clipboard. Click Download to save as a .json file. Need compact JSON for production? Click Minify to compress it. Use Clear on the input panel to start fresh. All processing runs in your browser with JSON.parse() and JSON.stringify().

When You'd Actually Use This

API Development

API responses often come minified. Format them to understand the structure, debug issues, or document endpoints. Works the same for a REST response, a Swagger/OpenAPI spec saved as JSON, or a GraphQL response body.

Config File Review

Reviewing JSON configuration files? Format them first to see the structure clearly. Makes it easier to spot errors, understand settings, or compare different configurations.

Learning JSON

New to JSON? Formatting helps you understand the syntax. See how objects nest, how arrays work, and how data structures are organized. Much easier than reading minified code.

Debugging

Trying to find a bug in your JSON? If it doesn't parse, the error message points at the spot. If it does, the indentation makes wrong nesting easy to see, like a field that ended up inside the wrong object.

Common Questions

Is my JSON data stored?

No. All formatting happens in your browser using JavaScript's native JSON.parse() and JSON.stringify(). Your data never leaves your computer.

What JSON formats are supported?

We support all valid JSON according to the ECMA-404 standard. Objects, arrays, nested structures, strings, numbers, booleans, null - everything standard JSON supports.

Can I format invalid JSON?

No. The formatter parses your JSON first. If it's invalid, you'll see the parser's error message, which in most browsers includes the line and column. Fix the syntax error and the output updates. For common mistakes like trailing commas or single quotes, the JSON Fixer can repair them for you.

What indentation does it use?

We use 2 spaces for indentation, which is the most common standard. This makes nested structures easy to read without taking up too much space.

How big can my JSON file be?

Since processing happens in your browser, performance depends on your device. Small files format instantly. Very large files (10MB+) might take a few seconds, but they'll still work.

Can I customize the formatting?

Currently, we use standard 2-space indentation. If you need different formatting options, consider using command-line tools like jq for advanced customization.

Other JSON Tools You Might Need

Formatting is just one JSON task. Here are other tools that work well together: