How it works
How to use the JSON5 Validator
Paste JSON5
Comments, trailing commas, unquoted keys and single-quoted strings are all allowed.
Read the report
Errors are underlined with their exact line and column.
Convert if needed
A valid document is shown as strict JSON too.
What is JSON5?
JSON5 is a superset of JSON designed for hand-written config files. It allows comments, trailing commas, unquoted object keys, single-quoted strings, hexadecimal numbers, leading/trailing decimal points, Infinity and NaN. Tools such as Babel and many build systems read JSON5 configs.
Built for developers
Why developers use it
Private by design
Runs 100% in your browser. Nothing you paste is uploaded, logged or stored on a server.
Instant results
Output updates as you type, with precise error locations when something is wrong.
Works offline
Once loaded, the tool keeps working without a connection. Install it as an app if you like.
Free, no sign-up
No accounts, no limits, no watermarks.
FAQ
Frequently asked questions
Can I use JSON5 where JSON is expected?
Not directly — most JSON parsers reject JSON5 features. Convert it to strict JSON first (the validator shows the result).
Is my data uploaded anywhere?
No. Everything runs locally in your browser — nothing you paste or open is sent to a server, logged or stored. The tool keeps working offline once the page has loaded.
Keep going
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