Pushover
Simplest curl command in one line
$ curl -s --form-string "token=abc123" --form-string "user=user123" --form-string "message=hello world" https://api.pushover.net/1/messages.json
For better reading
curl -s \
--form-string "token=abc123" \
--form-string "user=user123" \
--form-string "message=hello world" \
https://api.pushover.net/1/messages.json