How to use the JSON formatter
Paste or type JSON into the input. The tool validates it as you type. If it is valid you get a formatted, syntax-highlighted version you can copy, minify, sort or download. If it is invalid you see the exact line and column with a plain-English message.
Common JSON errors and how to fix them
- Unexpected token in JSON
- Trailing comma
- Single quotes instead of double quotes
- Unexpected end of JSON input
- Property names must be double-quoted
- Bad escaped character
FAQ
Why is my JSON invalid?
The most common reasons are trailing commas ([1,2,]), single quotes instead of double quotes, unquoted keys ({a:1}), comments, and missing commas between fields. Paste your JSON above — we show the exact line and column.
What does Auto-fix change?
It removes comments and trailing commas, converts single quotes to double quotes, quotes bare keys, converts Python True/False/None to true/false/null, inserts missing commas and closes unclosed brackets. Every change is listed so you can review it.
Is my data sent to a server?
No. Formatting, validation and Auto-fix run 100% in your browser. Only when you press Explain with AI is the JSON sent to our AI service to generate a hint.
Can JSON have comments?
Standard JSON (RFC 8259) does not allow comments. Formats like JSON5 and JSONC do, but most APIs reject them.