JSON Formatter
Format, minify and validate JSON, with the exact line and column of any error.
Runs locally in your browser. Your input is never sent anywhere.
What this does
Formatting re-indents JSON so it is readable; minifying strips every byte of insignificant whitespace, which is what you want before sending it over the wire. Both run entirely in your browser.
Reading the errors
When JSON is invalid you get the reason plus the exact line and column, for example
Unexpected token , at line 3, column 8. Browsers word these messages
differently and some omit the position entirely, so this tool locates the error
itself and reports the same position everywhere.
A note on very large numbers
JSON numbers are parsed as IEEE-754 doubles, so an integer beyond about 9×1015 loses precision — a limitation of JavaScript itself, not this tool. If you are handling large IDs, transmit them as strings.