Kill Bill is the open-source subscription billing and payments platform.
- Subscription engine, with plans management (trial, upgrade, downgrade, etc.), support of add-ons, bundles with multiple subscriptions
- Invoicing engine, supporting different billing alignments, recurring and one-time charges, international tax, metered billing
- Payment state machine, with payment routing capabilities, supporting dozen of gateways
- Plugin architecture, which allows further customization with your own business logic, in Java or Ruby
You can find more information on killbill.io.
Kill Bill is released under the Apache license 2.0.