arXiv is a free distribution service and an open-access archive for 2,110,790 scholarly articles in the fields of physics, mathematics, computer science, quantitative biology, quantitative finance, statistics, electrical engineering and systems science, and economics.
eFunda stands for engineering Fundamentals. Its mission is to create an online destination for the engineering community, where working professionals can quickly find concise and reliable information to meet the majority of their daily reference needs.
WolframAlpha is a computational knowledge engine that generates output by doing computations from its own internal knowledge base, instead of searching the web and returning links. WolframAlpha includes specialized resources for engineering, materials, computational science, and chemistry.
FreeCAD is an open-source parametric 3D modeler made primarily to design real-life objects of any size. FreeCAD is multiplatform, highly customizable, and reads and writes in a wide variety of file formats.
QCAD is a free, open source application for computer aided drafting (CAD) in two dimensions (2D). With QCAD you can create technical drawings such as plans for buildings, interiors, mechanical parts or schematics and diagrams. QCAD works on Windows, macOS and Linux.
The National Technical Information Service is a central resource for accessing government-funded scientific, technical, engineering, and business related information. The NTRL Database for access to full text technical reports and bibliographic records for technical reports.
The American Society of Mechanical Engineers (ASME) is an American professional association that, in its own words, "promotes the art, science, and practice of multidisciplinary engineering and allied sciences around the globe."