A toolchain in software development is a collection of tools or a toolbox, that are used one after another to develop software.
Cloudogu EcoSystem Toolchain
The specialty of the CES toolchain is, that it is not just a toolbox. It is a selection of open source tools that are interlinked. An example of a Continuous Delivery Pipeline is described in our blog posts "Continuous Delivery 4" and "Example setup of continuous integration platform".