Selkie (2019-2022) is a collaborative marine energy research and development project funded by the European Union’s Ireland-Wales Cooperation Programme. Its aim is to develop a set of multi-use tools, templates, standards, and models in key shared technology areas. These tools will be developed in partnership with, and for the benefit of, marine energy industry stakeholders and will be made available, open-source, upon the conclusion of the project. The present report constitutes the first deliverable (D5.1) in work package 5 of the Selkie project, which focuses on foundation and mooring system design. Beginning with an overview of the available technologies and design approaches, the report reviews existing tools for foundation, anchor, and mooring system design with a particular focus on open-source software tools and their applicability to marine energy projects. Its findings will be used to inform the research undertaken in work package 5 and the development of the corresponding Selkie design tool.