nBill Lite is a FREE cut down version of nBill, the mobile-friendly billing component for the Joomla Content Management System. It allows you to create invoices which can be e-mailed to your clients and paid for online. The lite edition does not support automatic generation of recurring invoices, but the standard edition does (among many other things!).
nBill Lite is free of charge to download and use, and is released under the GPL v2 open source license. Support for nBill Lite is available for a fee. nBill Lite v3 onwards requires PHP 5.4 or above.