LeafyGreen is MongoDB's open-source product design system, a React UI kit and CSS pattern library built with CLI tooling, documented on the mongodb.design site.
The visual system deliberately splits into two modes, a dark, neon-green hero/feature layer and a lighter, teal-gray content layer, a distinctive contrast pattern worth studying for developer-tool products that need both a bold marketing presence and a calmer, dense working interface.
Developers building developer-facing tools or database-adjacent products who want a real, installable React component library built around a database company's own dark-mode-forward brand.
It's genuinely open source with CLI tooling included, so components and scaffolding can be pulled directly into a project rather than only referenced.
MongoDB's design system, documenting the components used across its internal products.
