Concourse is an open source automation system, used mainly for CI/CD. You describe pipelines in YAML, built from resources, tasks and jobs: resources are external sources such as a Git repository, tasks each run in their own container, and jobs form a dependency graph from source code to production. You manage pipelines with the fly command-line tool and follow them in a web interface. Concourse is written in Go and available under the Apache-2.0 licence.
Concourse is a software project, not a hosted service: you download the server and the fly CLI and run them yourself, for example with systemd or Docker Compose. This means you decide where pipelines, source code and secrets are processed. The project began at Pivotal in 2014 and was open sourced in 2015. According to its governance repository, the project is joining the Cloud Foundry Foundation, whose governance mechanisms will apply. For a European organisation, Concourse is a CI/CD system that can run entirely under its own control, without depending on an external cloud provider.