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.
JSDelivr is a free public CDN for open-source projects. It can serve web files directly from the npm registry and GitHub repositories without any configuration.
Stripe offers online payment processing for internet businesses as well as fraud prevention, invoicing and subscription management.