How json validator works
The JSON validator parses your text with the standard JSON parser. If parsing succeeds it reports valid and shows a structural summary of the document — its root type (object, array, string, number, boolean or null), the number of keys or elements, the byte size, and a pretty-printed copy.
When parsing fails, JavaScript throws a SyntaxError whose message includes the byte position of the problem (for example "Unexpected token in JSON at position 42"). The validator extracts that position and converts it to a one-based line and column by counting the newlines before it, so you can jump straight to the offending character — even in a multi-line JSON document.
Common causes of invalid JSON are single quotes instead of double quotes, trailing commas after the last item, missing commas between items, unquoted keys, or an extra closing brace. The error message names the first problem the parser hit. Everything runs locally in your browser; your JSON is never uploaded.
Frequently asked questions
How is this different from the JSON formatter?
The JSON formatter pretty-prints valid JSON. This validator leads with a clear valid/invalid verdict and, on failure, pinpoints the exact line and column of the syntax error so you can fix a broken document instead of guessing.
How does it find the error location?
When the built-in JSON parser fails it reports the byte position of the problem. The validator reads that position and converts it to a 1-based line number and column by counting the newlines before it.
What makes JSON invalid?
The usual suspects are single quotes instead of double quotes, trailing commas after the last item, missing commas between items, unquoted object keys, or an unbalanced brace or bracket. The error message names the first one the parser encounters.
Is my JSON sent to a server?
No. Parsing and validation happen entirely in your browser using the built-in JSON parser. Nothing is uploaded or stored, so it is safe for sensitive configuration files.
