Concourse is an open source continuous integration (CI) tool written in Go. Concourse was dreamt up and built while working on the Cloud Foundry project and experiencing the interesting CI and CD challenges that it has. Concourse limits itself to three core concepts: tasks, resources, and the jobs that compose them. Interesting features like timed triggers and synchronizing usage of external environments are modeled in terms of these, rather than as layers on top. With these primitives you can model any pipeline, from simple (unit, integration, deploy, ship) to complex (testing on multiple infrastructures, fanning out and in, etc.). There are no more nooks and crannies of Concourse introduced as your pipeline becomes more involved.