"droppy" is the second version and complete
rewrite of "dropbox".
dropbox was a system where you and other users can upload
("drop") their files to share them with others and/or
create online backups of them, and so is droppy.
in addition to complete rewritten code, droppy gained a well-looking new design and some web-two-zero feeling (for example, it catches errors while logging in or registering via ajax and displays them instantly in the window instead of reloading the whole site).