Sketch App Kits

Sketch App Sources - Free design resources and plugins - Icons, UI Kits, Wireframes, iOS, Android Templates for Sketch

Invision kits

Free UI design kits

Uplabs

Unlimited UI Kits, Icons, Templates, Themes and More - UpLabs

Figma UI Kits

UI Kits for Figma - Free Figma Templates, UI Kits & Resources

UI8 Freebie

Adobe XD Kits

Adobe XD UI kits - The best free XD UI kits on XDGuru

IOS Design Kit

iOS Design Kit - Library of iOS app templates and UI elements - iOS 13 GUI

Other resources