25+ Free Bootstrap UI Kits and Templates @Creative Tim
Free PSD Bootstrap Basic Elements - DumboUI Kit
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.
20 Free Bootstrap UI Kits
Iwo Web UI Kit - Headers & Covers - PSD Photoshop, Graphic Templates - Envato Elements