Hide curl output

From man curl

-s, --silent Silent or quiet mode. Don't show progress meter or error messages. Makes Curl mute. It will still output the data you ask for, potentially even to the terminal/stdout unless you redirect it.

So if you don't want any output use:

curl -s 'http://example.com' > /dev/null

This one looks more elegant to me:

curl --silent --output /dev/null http://example.com

Also, if you want to see the HTTP code:

curl --write-out '%{http_code}' --silent --output /dev/null http://example.com

Full documentation is here.