Public and Private Project Sharing
Most of GUI design tools propose to share projects to others in order to get a feedback. That's considered handy feature as as well as frequently used one. At Mockup Builder we had this feature working, but sharing was implemented as public only, due to lack of profile assignment features as well as account management.
Now Mockup Builder prototyping design tool proposes "Private sharing" feature, if user logged in and selected some of our trial plans users can send designed screens to others privately. Links now won't be visible in public.