Phoenix Startup UI Kit is a versatile tool to kickstart a landing page. It cointans 110 ready to use HTML5 cards coming with Sketch and PSD resources. With Phoenix Startup UI Kit it's really easy and joyful to create landing pages.
Untitled719 is a collection of over 120 iOS screen templates for Sketch that are logically connected with each other and combined into 6 app prototypes, matching the most popular App Store categories. All templates look flawless on every iPhone, including iPhone X, iPhone 8 and even iPhone SE.
CSS Mint is a lightweight (just 3KB gzipped) and fully-responsive open source UI kit built to ease up layout and structuring of your web application. Built on top of normalize.css, it handles cross browser inconsistencies and provides minimalistic CSS components to be used in your application.