Frameworks

Semantic UI: Semantic empowers designers and developers by creating a shared vocabulary for UI
Bootstrap: Bootstrap is a free and open-source CSS framework directed at responsive, mobile-first front-end web development. It contains CSS- and JavaScript-based design templates for typography, forms, buttons, navigation, and other interface components
Material-UI: React components for faster and easier web development. Build your own design system, or start with Material Design

Illustrators

unDraw: Open-source illustrations for any idea you can imagine and create.
paid Iconscout: Get high-quality Icons, Illustrations and Stock photos at one place

Semantic UI React: The official Semantic-UI-React integration
React-Bootstrap: Bootstrap 4 components built with React.
paid Material Kit React: Material Kit React is a Free [email protected] Kit with a fresh, new design inspired by Google's material design
@zeit-ui/react: React implementation for styles originating from Vercel's design.
Ant Design: A design system for enterprise-level products. Create an efficient and enjoyable work experience
Ant Design Pro: Out-of-box UI solution for enterprise applications
Blueprint: A React-based UI toolkit for the web

Ant Design Motion: Use Ant Motion to quickly use animations in the React framework

Ant G2Plot: G2Plot is an interactive and responsive charting library based on the grammar of graphics, which enables users to generate high quality statistical charts through a few lines of code easily
Devextreme Reactive: Data-Centric React Components for Bootstrap and Material-UI

https://cogoport.github.io/cogo-toast/: Beautiful, Zero-Configuration, Toast Messages

[react-flip-move](https://github.com/joshwcomeau/react-flip-move): This module was built to tackle the common but arduous problem of animating a list of items when the list's order changes