CEASIOMpy is an open source conceptual aircraft design environment. CEASIOMpy can be used to set up complex design and optimization workflows, both for conventional and unconventional configurations. CEASIOMpy provides tools for various disciplines in aircraft design, amongst others: Geometry and meshes, weight and balance, aerodynamics, structures, mission analysis, stability analysis. CEASIOMpy uses the open-standard format CPACS. Workflows can be set up with the open-source environment RCE. Both CPACS and RCE are actively developed by the German Aerospace Center DLR. Follow the links below to learn how get started or how to contribute to the project. CEASIOMpy uses surrogate models to speed up the creation of aerodynamic databases.