This is a list of all the available free photo management and editing software that I am aware of:
The 5 best free photo editing programs
digiKam – Library management, with editor (can handle Raw).
darktable – Raw editor (with basic library management)
RawTherapee – Raw editor
Gimp – Image editor (can handle Raw). Not super user friendly
Luminance HDR – Makes HDR images
There are many other free
Lightzone – Image editor. Can handle Raw but doesn’t save changes to a database/sidecar files.