Format messy or compressed JSON so it is easy to read.

JSON formatter and syntax validator. Re-indents JSON with configurable tab/space indent, validates structure, and reports parse errors with line and column.

JSON.parse for validation and normalisation, JSON.stringify with replacer and space argument for formatting. Indent options: 2-space, 4-space, tab. Sort keys option available (alphabetical, depth-first). Error reporting uses the browser's native JSON parse error message which includes byte offset.