JSON Validator

JSON looks simple but is surprisingly easy to break — a missing comma, an unquoted key, a stray trailing comma, or a misplaced bracket can all turn valid-looking JSON into a parse error. The official JSON specification (RFC 8259) is strict: keys must be double-quoted, no comments are allowed, and trailing commas are forbidden. Relaxed variants like JSON5 or jsonc support these conveniences but produce output that is not standard JSON.

A dedicated validator gives precise, actionable error messages — including the character position of the problem — so you can fix syntax issues quickly rather than squinting at a wall of braces. Utilify's validator uses your browser's native JSON.parse, which guarantees the same behavior as the production JavaScript runtimes your code actually runs on. Everything runs locally; your payload never leaves the page.

The errors people hit most often are predictable. Single quotes instead of double quotes around strings and keys; a comma after the last element of an array or object; copying a JavaScript object literal (where unquoted keys are legal) and expecting it to be valid JSON; "smart" curly quotes pasted from a word processor; and an unescaped newline or backslash inside a string. Each of these produces a clear parse error here, positioned so you can jump straight to the offending character.

Validating is not the same as formatting. A formatter assumes the input is already valid and rearranges its whitespace; a validator decides whether the input can be parsed at all, and tells you exactly where it fails if not. Run the validator first when you are debugging a payload of unknown origin — an API response, a webhook body, a hand-edited config file — and only format once it parses cleanly.

One distinction worth keeping in mind: syntax validation is not schema validation. This tool confirms that your JSON is well-formed and parseable. It does not check that required fields are present, that a value is a number rather than a string, or that an enum holds an allowed value — those are JSON Schema concerns, a separate layer that runs on top of valid JSON.