JSON Validator

"Is this valid JSON?" sounds like a yes-or-no question, and most validators treat it that way — a green check or a red X, maybe a generic "Unexpected token" message copied straight from the JavaScript engine. That's enough to know something's wrong, but not enough to fix it quickly, especially in a large payload where the actual problem could be anywhere.

This validator surfaces the exact line and column where parsing failed, extracted directly from the parser's own error, along with the specific line of text so you can see it in context immediately. Then it goes a step further: since a bare parser error rarely explains the root cause in plain terms, it checks the input for the small set of mistakes that account for the overwhelming majority of real-world JSON failures — a trailing comma before a closing bracket, single quotes where JSON requires double quotes, an unquoted object key, or a // or /* */ comment (none of which are valid JSON, even though all four are completely normal in a JavaScript object literal, which is where the confusion usually comes from).

For validation that goes beyond "is this syntactically correct JSON" into "does this data actually have the shape I expect," there's an optional JSON Schema check. Paste in a schema alongside your JSON and it validates structure, required fields, and value constraints — supporting the core keywords most people actually use (type, required, properties, items, enum, minimum/maximum, minLength/maxLength, pattern) rather than promising full compliance with the entire JSON Schema specification, which includes a long tail of advanced keywords (like $ref, allOf/anyOf/oneOf combinators, and format validators) that add significant complexity for relatively rare use cases.

Both checks run entirely in your browser. Nothing you paste in — whether it's a sanitized test fixture or a real payload with production data in it — is ever sent anywhere to be validated.