JSON formatter
Paste JSON to pretty-print it with configurable indentation, minify it to a single line, sort keys alphabetically, or pinpoint a syntax error by line and column number.
No uploads · Everything runs in this browser
FAQ
Is my JSON sent to a server?
No. Parsing and formatting happen entirely in this browser, so API responses and config files stay on your device.
Why do long numbers stay exact?
Many formatters use JSON.parse, which rounds integers larger than 9007199254740991. This tool keeps the original digits of every number.
What is the maximum JSON size I can format?
There is no hard size limit. Files up to a few megabytes format instantly. Very large JSON (tens of megabytes) may be slow depending on your device.
Can I sort JSON keys alphabetically?
Yes. Enable the "Sort keys" option before formatting, and all object keys will be sorted A to Z recursively.
What does the error message show?
When the JSON is invalid, the tool shows the line and column of the first error and jumps to it in the input so you can fix it immediately.