GitHub - bootflat/Bootflat.UI.Kit.PSD: Bootflat UI Kit is PSD User Interface Pack including a set of beautiful and pure components, which you can use to create startup projects, websites or iOS/Android Apps.
55+ Best Free PSD Flat UI Kits - DesignMaz
100+ Best Free PSD UI Kits - Freebiesbug
Free UI Kits Web Graphics PSD File Download - freshDesignweb