Lightning Design System is described as 'Salesforce Lightning Design System is the UI kit tailored for building Salesforce apps: Using the Lightning Design System markup and CSS framework results in UIs that reflect the Salesforce Lightning look and feel' and is an app in the Development category. There are more than 10 alternatives to Lightning Design System for Self-Hosted solutions, React and Online / Web-based. The best alternative is UIkit, which is both free and Open Source. Other great apps like Lightning Design System are Semantic UI (Free, Open Source), Material Bread (Free, Open Source), BlueprintJS (Free, Open Source) and Reakit (Free, Open Source).
React-based UI toolkit for the web. It is optimized for building complex, data-dense web interfaces for desktop applications which run in modern browsers and IE11. This is not a mobile-first UI toolkit.
This project's goal is to be able to create a fully accessible material design styled website using React Components and Sass. With the separation of styles in Sass instead of inline styles, it should hopefully be easy to create custom components with the existing styles.