# minifying some CSS
curl -X POST -s --data-urlencode 'input=p { color : red; }' https://www.toptal.com/developers/cssminifier/raw
# minifying a CSS file (e.g. style.css -> style.min.css)
curl -X POST -s --data-urlencode 'input@style.css' https://www.toptal.com/developers/cssminifier/raw > style.min.css
Click on the language of your choice to see an example: