For general information about Kill Bill, including its features, visit the FAQs on our website.

How stable are your APIs?

We have two release trains:

  • The latest release with an even minor number (e.g., 0.22.x) is stable (APIs are backward compatible).

  • The development team uses odd minor numbers for developing new features (0.17.x, 0.19.x, 0.21.x, etc.). API and DDL changes are frequent.

What kind of tests do you perform?

Before each release, there are thousands of tests that we perform:

  • Unit tests

  • Functional tests

  • Java library integration tests

  • Server integration tests to check the REST APIs

  • Client APIs integration tests

However, note that Kill Bill is a platform to build billing systems. There are many combinations of configurations possible, and we cannot test them all. We provide a test framework to help you verify your system before going to production.

Also, take extra care when installing third-party plugins. Only the plugins hosted on our killbill organization on GitHub are officially supported.

Where is the code?

Our code is hosted on GitHub, in the killbill organization.

We are not a Java shop. Can we still use Kill Bill?

Yes! We try to hide most of the complexity, so you can simply use Kill Bill as a service, using our client libraries. Currently, plugins can only be written in Java or Ruby.

What is a (subscription) bundle?

A bundle is a collection of subscriptions. A typical bundle has exactly one BASE subscription and a collection of ADD_ONs. Logically grouping these subscriptions makes it easier to automatically cancel all ADD_ONs when the BASE subscription is canceled, for example.

Can I create subscriptions without billing information?

Yes! If you are not ready to charge your customers (for example, during an activation phase), you can configure your plan with an initial free phase. Alternatively, you can set the AUTO_PAY_OFF tag on the customer account, and Kill Bill generates invoices but won’t attempt to charge them. When you decide to remove this tag, payments will automatically occur.

Can I create an account without a subscription?

Absolutely! Having an account without a subscription is useful during onboarding flows. For example, you may need your customer in your CRM engine, databases, and so forth before she has signed up.

What are the environment requirements?

Specifying definite environment requirements is tricky because it depends on the plugins you want to run, your expected traffic, etc. If in doubt, ask the Kill Bill Community (mailing-list). Remember to provide your details!

How can I listen to Kill Bill events?

You can either write a custom plugin (all Kill Bill events are visible to plugins) or register an endpoint that Kill Bill will send events to via HTTP POST (check our push notifications documentation).

Do you track any usage data in Kill Bill?

When Kill Bill starts up, it reports anonymous data to Google Analytics for development purposes. The core development team is primarily interested in:

  • Java vendor and version (we’ve caught some jdk bugs in the past)

  • Deployment environment, such as the OS and Servlet container used

  • Kill Bill version (helps us decide our EOL policy)

Data is anonymous and not shared with any third party, and no financial data is collected. You can find the code here.

To disable tracking, specify org.killbill.server.updateCheck.skip=true in your killbill.properties.

We are relying on this data to help us focus our development efforts. If your environment prevents you from sharing this automatically, but would like to help, please reach out to the Community (mailing list) instead and describe your deployment. Thanks in advance!