ISPConfig is a widely used free, open source hosting control panel for Linux, licensed under BSD license. ISPConfig enables to manage one or more servers from one control panel. HostBill integration with ISPConfig control panel enables to sell shared hosting services with full automation of account provisioning, upgrades and downgrades of the hosting plan. Client can not only display access details in client area but also quickly change the password. Admin area is where you can control account lifecycle and billing information.