Awesome Bootstrap 4  

A curated list of awesome Bootstrap 4 resources:

Official

• Bootstrap 4 - Official Bootstrap 4 site.

Themes

• Bootstrap 4 cc - Bootstrap 4 open sourced libraries, themes & templates.
• GetBootstrap - Freshly made & build bootstrap 4 themes.

Generic plugins and extensions

• Bootstrap Layouts - Generic Bootstrap 4 layouts.

UI Kits

• Material Design for Bootstrap - Powerful and free UI KIT for Bootstrap 4. (source)

Integrations

• bootstrap-vue - Vue.js 2 Twitter Bootstrap 4 Components
• ng-bootstrap - Angular 2 Bootstrap 4 components, built by the angular-ui Team. (source)
• reactstrap - ReactJS Bootstrap 4 components
• react-bootstrap - Better reimplmenetation of reactstrap, Bootstrap components built with React

Showcases

• Built With Bootstrap - List of Great websites built with bootstrap.

Tutorials

• Hackr.io - Bootstrap Tutorials and Courses

Docs

• Bootstrap 4 Beginner's Guide to pro - Best way to learn Bootstrap 4 for beginners.
• Awesome Bootstrap 4 - A curated list of awesome Bootstrap 4 resources.

More awesomeness is coming, stay followed.