BuildStream is a Free Software tool for building/integrating software stacks. It takes inspiration, lessons and use-cases from various projects including OBS, Reproducible Builds, Yocto, Baserock, Buildroot, Aboriginal, GNOME Continuous, JHBuild, Flatpak Builder and Android repo. BuildStream supports multiple build-systems (e.g. autotools, cmake, cpan, distutils, make, meson, qmake), and can create outputs in a range of formats (e.g. debian packages, flatpak runtimes, sysroots, system images) for multiple platforms and chipsets. This package provides the documentation for BuildStream.