Prefab is a set of software tools for reverse engineering graphical interfaces from their pixels. Prefab supports a variety of features for modeling the appearance of interface elements, identifying those elements in pixels, and applying semantic metadata to those elements. Prefab reverse engineers interfaces many times per second, making it possible to completely modify existing applications at runtime, independent of their underlying source code.

Prefab is written in C# and runs on Windows. However, because it only relies on the pixels of an interface, it can be combined with a remote desktop or virtual machine client to reverse engineer applications that run in Mac, Linux, or any other OS.

Prefab is the creation of the University of Washington Dub Group http://dub.washington.edu.