GrabCAD is described as 'No need to reinvent the wheel! Someone else has solved that CAD problem or designed that bolt. The GrabCAD Library has the models and knowledge you need in the world's largest collection of free CAD files' and is a CAD software in the backup & sync category. There are more than 10 alternatives to GrabCAD, not only websites but also apps for a variety of platforms, including Android, iPhone, Android Tablet and iPad apps. The best GrabCAD alternative is Thingiverse, which is free. Other great sites and apps similar to GrabCAD are Wikifactory, Ultra Librarian, Cults. and STLFinder.