Validate JSON

JSON validation checks whether a string is syntactically correct JSON — matching brackets, properly quoted keys, valid escape sequences, and no trailing commas. A validator reports the exact line and column of every error so you can fix issues without guessing.

The most frequent errors are: trailing commas after the last item (valid JavaScript but not JSON), single-quoted strings (JSON requires double quotes), unquoted keys, missing commas between elements, and unclosed brackets or braces. The validator reports the exact line and column of each error so you can fix them directly.

JSON validation checks syntax correctness — proper brackets, quoted keys, no trailing commas. JSON Schema validation goes further, checking that data matches a defined contract: required fields present, values of the right type, strings matching patterns. This tool checks syntax only. Use the JSON Schema Validator tool for contract validation.

The validator follows RFC 8259, the current JSON standard. RFC 8259 does not allow comments, trailing commas, NaN, Infinity, or single-quoted strings. These are features of JSON5 or JSONC. If your input uses those extensions, strip them (or convert to standard JSON) before validating.

Yes. The auto-repair feature removes trailing commas, converts single-quoted strings to double-quoted, and adds missing quotes around bare keys. It cannot fix structural errors like conflicting types or corrupted data — those require manual review at the highlighted error location.