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About JSON Validator Online
This tool validates JSON documents against the official RFC 8259 specification. Paste your JSON, and the tool either confirms it's valid or returns a precise error message — including the line and column where the syntax problem starts.
JSON validation catches the everyday mistakes that break parsers: missing commas between properties, trailing commas after the last property, unescaped quotes inside strings, mismatched braces or brackets, and the use of single quotes instead of double quotes for keys.
Use it when debugging API responses, when authoring config files by hand, or when constructing JSON in a template that gets concatenated together — the precise error pointer saves minutes of squinting at long files.
How to use this tool
How to check whether a string parses as valid JSON
Paste the JSON
Drop the candidate text into the "JSON" field. Both objects (`{ … }`) and arrays (`[ … ]`) parse. Trailing commas, single quotes, and comments are NOT valid JSON and will be flagged.
Press Run
Result returns `valid` (boolean), and on failure an `error` string describing roughly where parsing broke (line/column if the parser provides it). Success doesn't reformat — the input is unchanged.
Common error shapes
`Unexpected token } in JSON` usually means a trailing comma; `Unexpected end of JSON input` means an unclosed `{`, `[`, or `"`; `Unexpected non-whitespace character` after a complete value means extra text after the document.
Not a schema check
This validates SYNTAX only — that the text is parseable JSON. It does NOT verify the data matches an expected shape; for that pair with `json-schema-validator-online` or a real validator library in your build.