AppSensor is an open-source OWASP project that enables building self-defending applications with attacker detection and automated response capabilities. There are many security protections available to applications today. AppSensor builds on these by providing a mechanism that allows architects and developers to build into their applications a way to detect events and attacks, then automatically respond to them. Not only can this set of capabilities stop and/or reduce the impact of an attack, it gives you valuable visibility and security intelligence about the operational state of your applications. The self-protection model benefits all types of applications. In particular, it has gained traction with developers operating in the cloud and on DevOps teams. The increased visibility and speed of response become critical at scale, and the need for this capability becomes evident. This presentation will cover AppSensor concepts, features, use cases, integrations, deployment models, and some lessons learned from deploying in the field.