flatpak-builder: flatpak-builder (sandboxing desktop application building tool) flatpak-builder: flatpak-builder: flatpak-builder is a tool for building flatpaks from sources. flatpak-builder: flatpak-builder: Site: https://github.com/flatpak/flatpak-builder/ flatpak-builder: flatpak-builder: flatpak-builder: flatpak-builder: flatpak-builder: flatpak-builder: