BlueprintJS is described as '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'. There are six alternatives to BlueprintJS for Self-Hosted solutions, React and Salesforce.com. The best alternative is Reakit, which is both free and Open Source. Other great apps like BlueprintJS are Elastic UI (Free, Open Source), Ant Design (Free, Open Source), Atlaskit (Free, Open Source) and Chakra UI (Free, Open Source).
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.