JSON Formatter & Validator

Format, minify and validate JSON — with exact error positions. Runs entirely in your browser, nothing is sent anywhere. ← Workbench

JSON

sort keys Ctrl+Enter formats

Result

What this tool checks

Strict JSON (RFC 8259): rejects trailing commas, comments, single quotes, NaN/Infinity, leading zeros and unescaped control characters — the same rules your browser's JSON.parse uses.
Exact error positions: the line and column of the first mistake, with a caret pointing at the offending character.
Duplicate keys are reported as warnings — the last value wins, exactly like every JSON parser.
Big integers stay exact: a value like 9007199254740993 is formatted as-is instead of being silently rounded to ...92 the way ordinary parsers do.
Key order is preserved exactly as written, and Ctrl+Enter formats in place.