There are many different web-hosting billing systems around, and your final choice depends on your needs. For example, we use our custom system. You can check most popular systems like BoxBilling or WHMCS to find out which one is the best for you. If you are looking for a free solution, try phpCoin.
Hostinger's Knowledge Base
Find articles and information about features, various troubleshooting guides,
and other technical information related to the Hostinger's services