Developer · PRACTICAL GUIDE

How to Format JSON and Find Common Syntax Errors

JSON represents data using objects, arrays, strings, numbers, booleans and null. Pretty-printing adds indentation so nested values are easier to inspect. It does not verify that the data matches your application’s expected structure.

Start with a small valid object

Paste {"name":"Ada","active":true} and run the formatter. The result places the keys on separate indented lines. To inspect a larger payload, identify the outer object or array first, then follow one nested branch at a time.

Fix syntax carefully

JSON requires double quotes around object keys and string values. Trailing commas and comments are not valid JSON. If parsing fails, check the reported error, then look for unmatched braces, missing commas and incorrectly quoted text. Do not delete content just to make the error disappear.

Watch numeric precision

This tool parses using JavaScript. Very large integer literals can lose precision when parsed and serialized. If an identifier must remain exact, represent it as a quoted string in your data model when appropriate. Keep an untouched copy of important source data.

Written for Global Tools Hub · Reviewed 11 November 2026