JSON Validator

About this tool

"Is this JSON valid?" sounds like a simple yes-or-no question, but the honest answer usually needs a location attached — because the difference between valid and invalid JSON often comes down to one character somewhere in a large document, and finding that character by eye is the slow part. This validator answers both halves at once: a clear pass/fail verdict, and when it fails, the exact line and column where parsing broke down, plus the surrounding text so you can see the problem in context rather than counting characters by hand.

Validating is a narrower job than formatting, even though the two often get bundled together in a single tool. A formatter takes valid JSON and makes it readable; a validator's only job is the yes-or-no check itself, which matters most when you don't actually want the input rewritten — checking a config file exactly as a colleague pasted it, verifying an API response body before you build logic around it, or confirming a JSON field survived a database round-trip unchanged. Keeping validation as its own focused tool means the input on screen is always exactly what you pasted, with nothing reformatted out from under you.

The most common real syntax errors are remarkably repetitive once you've seen enough of them: a trailing comma left after the last item in an object or array, single quotes used where JSON requires double quotes, an unescaped quote inside a string value, or a missing comma between two properties. This validator's error reporting is tuned around exactly those cases — reporting the position the parser identifies as the break point, translated into a 1-indexed line and column, with a short snippet of surrounding text so the error reads as "here's the problem" rather than a bare character offset.

Everything runs using your browser's native JSON parser — the same one your code will use if you're working in JavaScript — so there's no separate implementation to disagree with what your application will actually do at runtime. Nothing you paste is uploaded anywhere; validation happens as you type, entirely client-side.