Spectrum is the design system by Adobe. It’s comprehensive and includes a changelog as well. It’s catered towards both designers and developers since for an element (i.e. button, tooltip) CSS code and design file (in AdobeXD) are available.
User Testing is a well-known usability testing solution software for product teams. User Testing’s design system is called Toolkit and thoroughly lists all the user interface (UI) elements for both design and developer teams can utilize in their process.
BigCommerce’s design systems is meant to be accessible to everyone. Their team doesn’t share the developer specifics right away and only includes a text link to developer docs.
The Chicago Design System is the public visual identity of the City of Chicago. Compared to our design systems, it also includes a module about accessibility since inclusivity is an expectation from government websites.
Uber’s Base is a design system comprised of modern, responsive, living components. Base Web is the React implementation of Base, which is definitely catered more towards software engineers.