Initially written so the author could view his contacts photos on a black background, Darckr can also automatically enhance the display of your photos by adding drop shadows and borders if you want. Another useful feature Darckr offers you is the possibility to view only your public photos, or only your non-private photos. That way you can see what your photostream looks like to everyone else without having to logout from Flickr.
Darckr's other aim is at saving you time in your Flickr life. You can post comments on your contacts photos or fave them much more easily than in the standard Flickr interface. You can even use this interface to comment on and tag your own photographs.
Darckr uses the Flickr API to retrieve data so cannot let other people view unauthorized content. By default Darckr displays photos at a size that cannot exceed "Small" (240 pixels) and, unlike other viewers, Darckr allows you to "opt-in" to grant others access to larger sizes. Darckr presents and in no case copies your pictures. They remain on Flickr and other users see only what they are entitled to.
If you're a Flickr user and have granted access to Darckr, then you can view your own photos, or a gallery of your contacts photos, and if you're a friend or family view full contents of other people streams. You can also share permalinks to your Darckr stream for instance to publish your most interesting photos as a Darckr gallery.