Cerberus, in reference to the Greek mythology of the three-headed god, guardian of Hell, was the name given to the internal testing automation solution we decided to build internally in 2011. At that time, the ecosystem of existing solutions, being commercial or open source, was not fulfilling our requirements for end-to-end functional testing. In this article we will explain how our internal solution evolved from a Proof of Concept to a broader deploy in other major companies, to perform Continuous Delivery, Continuous Testing and Monitoring at scale.