JSON Formatter & Validator

JSON (JavaScript Object Notation) is the standard format APIs, config files, and browser storage use to represent structured data as plain text. It's built from just a few building blocks — objects (key-value pairs in curly braces), arrays (ordered lists in square brackets), strings, numbers, booleans, and null — but a single misplaced comma or an unclosed brace is enough to make the whole document unreadable to a parser.

Formatting takes minified or hand-typed JSON and re-indents it so the structure is easy to scan. Validating goes a step further: it confirms the document actually parses as valid JSON and tells you exactly where it breaks if it doesn't. This tool does both at once, entirely in your browser — nothing you paste here is sent anywhere.

• •Never leave a trailing comma after the last item in an object or array — standard JSON doesn't allow it, even though many programming languages do.
• •Wrap all object keys and string values in double quotes, not single quotes — JSON has no concept of single-quoted strings.
• •Validate a payload before sending it to an API. A parser error in production is a much more expensive place to catch a typo than right here.
• •Keep nesting shallow where you can. Deeply nested JSON is technically valid but painful for the next person (often future you) to read.
• •Use minified JSON for network payloads and formatted JSON for anything a human will read or diff in version control.