JSON Formatter & Validator

What is a JSON Formatter?

A JSON formatter takes messy, minified, or poorly indented JSON data and reformats it with proper indentation and line breaks. This makes it much easier to read, debug, and understand the structure of your data. Whether you're working with API responses, configuration files, or database exports, a formatter helps you see what's actually in your JSON.

This tool also validates your JSON as it formats. If there's a syntax error — a missing comma, an unquoted key, a trailing comma — you'll see a clear error message pointing to the exact location of the problem.

How to Format JSON Online

1. Paste your JSON into the input field on the left (or upload a .json file)
2. Select your preferred indent size: 2 spaces, 4 spaces, or tabs
3. Click Format or press Ctrl+Enter — the formatted output appears on the right
4. Click Copy to copy the result to your clipboard, or Download to save it as a file

The tool also auto-formats when you paste, so in most cases you won't even need to click a button.

What is Valid JSON?

Valid JSON follows a strict syntax defined by json.org. The most common rules:

• Strings must be in double quotes — single quotes are not valid
• Object keys must be strings in double quotes
• No trailing commas after the last element in an object or array
• No comments — JSON does not support // or /* */ style comments
• Numbers cannot have leading zeros (except 0 itself or 0.x)
• The top-level value must be an object, array, string, number, boolean, or null

If your JSON has common errors like trailing commas or single quotes, use the Fix Errors button to auto-correct them.

JSON Formatter vs JSON Validator — What's the Difference?

A JSON validator checks whether text is syntactically correct JSON. It tells you "yes, this is valid" or "no, there's an error on line 14." A JSON formatter goes further — it re-indents and prettifies valid JSON so it's easy for humans to read. This tool does both: it validates first, then formats if the JSON is valid.

Why Use Our JSON Formatter?

• Fast — handles files up to 1MB without freezing
• Private — runs entirely in your browser; your data never leaves your device
• No signup — no accounts, no tracking, no paywalls
• Full-featured — format, minify, validate, sort keys, convert to CSV/YAML, compare two JSONs, fix common errors, and more
• Works offline — once loaded, the page works without an internet connection