JSON formatter and validator online - beautify and minify

• Trailing comma - {"a": 1,} is invalid.
• Single quotes - keys and strings must use double quotes.
• Unquoted keys - {a: 1} is a JavaScript object literal, not JSON.
• Comments - JSON (RFC 8259) has no comments; that is JSON5/JSONC.
• Raw newlines in strings - use \n.

Beautify (pretty print) adds indentation and line breaks so the structure is easy to read, review in Git and debug when inspecting an API response. Minify removes spaces, tabs and newlines outside strings, typically cutting the size by 20-40% and speeding up transfer. Example: { "a": [ 1, 2 ] } minified becomes {"a":[1,2]}.

Sort keys orders object keys alphabetically at every level (arrays keep their order). Run it on two versions of the same document and the differences line up, which makes comparing them much easier.

• object - {"key": value}, keys always in double quotes,
• array - [1, 2, 3],
• string - "London" (escapes: \" \\ \n \t \uXXXX),
• number - 42, -3.14, 1e6 (no leading zeros, no NaN or Infinity),
• booleans true/false and null.

Anything else - undefined, dates, functions, comments - is not JSON. Dates are usually sent as ISO 8601 strings such as "2026-10-11T09:30:00Z".

The validator reports the line, column and character position where parsing failed and shows a code excerpt with a caret. The reported spot is often after the actual mistake: a missing comma between items on line 12 is reported at the start of line 13, and an unclosed quote is only detected at the end of the document as “unexpected end of data”. Check the marked character first, then the token right before it.

The validator follows RFC 8259 / ECMA-404. Files with comments and trailing commas, such as VS Code settings, are JSON5 or JSONC and will be reported as invalid by JSON.parse.