OpenAIS is an open source implementation of the SA Forum (www.saforum.org) Application Interface Specification. The project currently implements APIs to improve availability by reducing MTTR. APIs available are cluster membership, application failover, checkpointing, eventing, distributed locking, messaging, closed process groups, and extended virtual synchrony passthrough. It is possible to write redundant applications that tolerate hardware, operating system, and application faults. Cluster software developers can write plugins to use the infrastructure provided by OpenAIS.