JSON Validator Online – Check JSON Syntax & Find Errors
Instantly validate any JSON string for syntax errors. Detects missing commas, unclosed brackets, invalid escape sequences, trailing commas, and all other JSON specification violations — with specific error messages to help you fix them.
Common JSON Errors and How to Fix Them
Our JSON validator detects all of these common errors and provides specific messages to help you fix them quickly:
What Is JSON Validation?
JSON validation is the process of checking whether a JSON string conforms to the JSON specification defined in RFC 8259. Valid JSON must follow strict syntax rules: all keys must be double-quoted strings, values must be one of the six allowed types (string, number, object, array, boolean, null), commas must separate all elements except the last one, and all opened brackets and braces must be properly closed.
Our free JSON validator online checks all of these rules instantly. When you click "Validate", it parses your JSON using the browser's native JSON parser and returns either a success message confirming valid JSON, or a specific error message identifying the exact problem so you can fix it immediately. This is especially important before sending JSON in API requests, storing it in databases, or including it in configuration files where a single syntax error can break an entire application.