What JSON Validator does
Validate syntax, UTF-8, depth, duplicate keys, unsafe JavaScript integers, and optional JSON Schema rules.
Also searched as validate, validator, check, lint, linter, verify, syntax check, is valid json.
Parse strict JSON
Apply safety and interoperability checks
Return structured diagnostics
Valid does not always mean portable
A syntactically valid number may still lose precision in JavaScript, and duplicate keys may be interpreted differently by consumers. Both are reported separately.
Useful diagnostics
Errors carry stable codes, source positions, expected/actual context, and a suggested next action.
JSON Validator FAQ
Does jsontools.me upload my JSON?
No. The document is parsed and processed by json-buf inside a dedicated WebAssembly worker on your device.
Does it work offline?
Yes. After the application shell and engine have loaded once, the installable PWA keeps the tools available without a network connection.