U.S. DOE designed this online directory -- and many of the tools it houses -- to help researchers, designers, architects, engineers, builders, and code officials evaluate and rank potential energy-efficiency technologies and renewable energy strategies in new or existing buildings. Visit the directory for more than 275 energy-related software tools, including databases, spreadsheets, component and systems analyses, and whole-building energy performance simulation programs. For each tool in the directory, a short description is provided along with other information including expertise required, users, audience, input, output, computer platforms, programming language, strengths, weaknesses, technical contact, and availability.