WHMCS - WHMCS is an all-in-one client management, billing & support system for online businesses.
Vanido - Vanido is a singing coach in your pockets.
HostBill - HostBill is a powerful and flexible, all-in-one automation, billing, client management and support platform for online businesses.
Singscope - See your pitch analyzed as you sing
Blesta - Blesta is professional client management, billing, and support software.
Listening Singing Teacher - Listening Singing Teacher helps you to sing in tune and in rhythm.