JSON Validator
Paste your JSON and instantly check if it is valid. See exact error messages with details.
JSON (JavaScript Object Notation) is the de-facto data interchange format for APIs, configuration files, and web applications. Even experienced developers frequently encounter JSON that fails to parse — a single missing comma, an unclosed bracket, or a trailing comma can break an entire application. This JSON Validator checks your JSON instantly against the official RFC 8259 standard and gives you a precise error message when something is wrong, saving hours of manual debugging.
📋 How to Use This Calculator
Paste your JSON into the input box — it can be anything from a single object to a deeply nested array. Click "Validate JSON" and the tool reports either a success message showing the number of lines and characters, or an error with the browser's native JSON parser message pointing to the exact issue. For common errors, look for: unquoted property names (JSON requires double quotes), trailing commas after the last item in an array or object, and single-quoted strings (JSON only allows double quotes). Fix the error, paste again, and re-validate.
💡 Key Facts & Information
JSON validation uses the browser's native JSON.parse() engine, which is the same parser used by Node.js and modern web browsers — so a "valid" result here means it will parse correctly in your application. JSON supports six data types: strings (must be double-quoted), numbers, booleans (true/false), null, arrays, and objects. A valid JSON document must have exactly one root element — either an object {} or an array []. Common pitfalls include JavaScript-style comments (not valid in JSON), undefined values, and dates (JSON has no native date type — use ISO 8601 strings instead).