JSON Formatter & Validator

How it works

The input is parsed with the browser's built-in JSON.parse, the same strict parser your JavaScript code uses, so if it validates here it will parse in production. Errors are reported with the line and column where the parser gave up. The actual mistake is usually just before that point: a trailing comma, a missing quote, or a single-quoted string.

Common JSON errors

• Trailing commas like [1,2,] are not allowed in JSON (they are in JavaScript).
• Single quotes: JSON strings and keys need double quotes.
• Comments are not part of JSON. Files such as tsconfig.json use "JSONC", which strict parsers reject.
• Big integers above 2⁵³ lose precision when parsed as JavaScript numbers. Keep IDs as strings.

FAQ

Is my JSON uploaded anywhere?

No. The page has no backend for this tool; parsing and formatting happen in JavaScript on your device. You can disconnect from the internet after the page loads and it keeps working.

Does sorting keys change the data?

No. Object key order has no meaning in JSON, so sorting only changes how it reads. Array order is never changed.