More and more designers and developers are looking for UI kits to make their lives easier and who can blame them? Not us! And we're even making it easier for you because we scoured the two biggest design showcase sites - Dribbble and Behance - and collected the UI Kits that received the most likes and upvotes. The best thing is that these are all free downloads.
Unique Freehand UI Kit
Modern IOS7 
Ready To Use UI 
Colorful Kit
Bold & Clean 
Complete IOS9 UI Kit
Bonus: Check out the Free UI Interface for iPhone.
Smart UI Mockup
Modern Vintage UI Kit
Perfect Grid 
Wooden UI Interface
If you're more old school, check out our Windows Graphical User Interface.