How to Format JSON Online — A Quick Guide

JSON (JavaScript Object Notation) is the most common data format used by web APIs, configuration files, and data storage. But raw JSON from an API response or log file often comes as a single unreadable line.

Why Format JSON?

Formatting (or “pretty-printing”) JSON adds proper indentation and line breaks, making it easy to:

• Debug API responses — quickly spot missing fields or unexpected values
• Validate structure — confirm your JSON is syntactically correct before sending it
• Share with teammates — formatted JSON is far easier to read in code reviews and Slack messages

How to Format JSON in 3 Steps

1. Paste your JSON into the input area
2. Click Format — the tool validates and pretty-prints your JSON instantly
3. Copy the result — use the Copy button or select all and copy

Minifying JSON

Sometimes you need the opposite — stripping all whitespace to reduce payload size. Our tool has a Minify button that compresses JSON to a single line, perfect for config files and API requests where every byte counts.

Common JSON Errors

If your JSON fails to parse, check for these common mistakes:

• Trailing commas — JSON does not allow a comma after the last item in an array or object
• Single quotes — JSON requires double quotes around strings and keys
• Missing quotes on keys — unlike JavaScript objects, JSON keys must always be quoted
• Comments — JSON does not support comments (use JSONC or JSON5 if you need them)

Pro Tips

Use the indent size selector to switch between 2 and 4 spaces — 2 is common for frontend projects, 4 for backend. The tool also shows a character count so you can track payload sizes.