Design systems reduce design inconsistencies, eliminate process bottlenecks, and allow teams and organizations to scale. A design system of systems is a platform that allows an organization to provide the same advantages across multiple platforms, channels, and even brands. Too often it can feel like designers and developers work in different worlds and speak different languages. These challenges are compounded multiple times when working with multiple user-facing interfaces across platforms, channels, or brands. We built a design system of systems using JS allowing all teams to stay on brand on all platforms and projects. This included a cross-brand and cross-platform components library for teams delivering digital experiences. At the core of the systems of systems is a common language, design tokens, that breaks down the barriers between designers and developers.