Developed by George Mason University and funded by the Mellon Foundation, "Tropy" is a new free app. designed to enable researchers to organize the chaos of photographs they take on research trips to archives.
(the name conveys the opposite of "entropy")
The American Historical Association's newsletter Perspectives on History includes an article about the creation of the app at
Documentation and a download button can be found at
Unfortunately the app does not manage .pdf documents. The developers say their next step is to provide cloud-based facilities to enhance collaboration.