Online JSON Lint

JSON Lint is a strict JSON linter — it parses your input under RFC 8259 rules and reports every place the document deviates from spec. Unlike a forgiving parser, it does not auto-correct anything. The point is to surface mistakes that real production parsers would also reject.

In practice they overlap heavily. A validator answers "is this valid?" with a yes/no plus an error location. A linter goes further: it points out every issue in one pass, gives a snippet around each one, and stays out of your way for valid input. JSON Pretty acts as both.

Trailing commas, single quotes instead of double, unquoted property keys, missing commas between items, unescaped characters inside strings, hidden byte-order marks at the start of files, and stray control characters that strict parsers reject.

No — and that is intentional. JSON Lint enforces strict JSON (RFC 8259). If you need a relaxed dialect, strip comments and trailing commas before linting, or use a different parser for storage and lint the canonical output before sending it to APIs.

No. The entire lint pipeline runs in your browser. JSON Pretty does not upload, log, or store your input. Sensitive payloads stay on your machine.

Yes. Linting runs off the main thread, so even multi-megabyte JSON files lint without freezing the page. You can paste raw text or upload a .json file directly.