The OpenID Connect protocol has quickly gained widespread adoption, enabling easy-to-use login and API access for both Web and native applications. During its development, extensive interoperability testing was performed on a voluntary basis to ensure that different implementations would actually work together. Now that the OpenID Connect protocol is final, the OpenID Foundation is working to ensure even better interoperation between implementations by creating a self-certification program for OpenID Connect implementations, with early participants including Google, Microsoft, NRI, Salesforce, and Ping Identity. This session will describe the certification test suite software developed by Roland Hedberg of Umeå University and how OpenID Connect implementers use it to certify their implementations to the OpenID Foundation.