27 Useful UI Design Elements & UI Kits for Designers

http://graphicdesignjunction.com/2014/04/ui-design-elements-ui-kits-for-designers/

50 Free Flat UI Kits For User Interface Designers

http://www.smashingapps.com/2014/04/15/50-free-flat-ui-kits-for-user-interface-designers.html#ixzz2zSTzmnXq

Free PSD Kits for Metro & Flat UI Design

http://www.webresourcesdepot.com/free-psd-kits-for-metro-flat-ui-design/

12 gorgeous free UI kits for 2014 to download

http://smashinghub.com/12-gorgeous-free-ui-kits-for-2014-to-download.htm

Flatastic Mobile UI Kit

http://thedesigninspiration.com/flatastic-mobile-ui-kit/

Flat Style & iOS 7 Line Style UI Kit PSD

http://www.graphicsfuel.com/2013/11/flat-style-ios-7-line-style-ui-kit-psd/

20 Flat Design Inspiraton Websites

http://cssmatter.com/blog/20-flat-design-inspiraton-websites/

Introducing the FlatPix UI Kit

http://designm.ag/resources/introducing-the-flatpix-ui-kit/

Flat UI Kits: 30 Free Kits For UI Design

http://blog.karachicorner.com/2013/11/flat-ui-kits/

31 Free Flat User Interface Kits

http://www.inspirationmix.com/flat-user-interface-kits/

25+ flat UI kits for web designers

http://www.webdesignerdepot.com/2013/11/25-flat-ui-kits-for-web-designers/

Free Download Sweet Candy UI Kit

http://ibrandstudio.com/freebies/sweet-candy-ui-kit

40 Absolutely Best Free Flat UI Kits

http://designbeep.com/2013/10/17/40-absolutely-best-free-flat-ui-kits/

Free Beautiful UI Elements For Your Next Web Application Design

http://www.onextrapixel.com/2013/10/22/free-beautiful-ui-elements-for-your-next-web-application-design/

11 Flat UI bootstrap themes and templates

http://smashinghub.com/11-flat-ui-bootstrap-themes-and-templates.htm

Lucent UI – A free, vector-based and retina ready UI kit

http://sarahjustine.com/2013/10/24/lucent-ui-a-free-vector-based-and-retina-ready-ui-kit/

100 Latest Free Flat UI Kits to Speed Up Your Web Design Process

http://www.icanbecreative.com/free-flat-ui-kits.html

75+ Latest Free UI designs PSD

http://www.cssauthor.com/latest-free-ui-designs-psd/

Trending Flat UI Design Kits for Free Download

http://iamdesigning.com/trending-flat-ui-design-kits-for-free-download/

Freebie: Free Flatic User Interface UI Kit PSD

http://pixel2pixeldesign.com/freebie-free-flatic-user-interface-ui-kit-psd/