What 21st does
21st is a platform and registry of community-made UI components and building blocks for the agentic internet. It functions as a repository where developers can discover, browse and use pre-built interface elements, providing both ready-made UI pieces and infrastructure for assembling applications quickly.
Key capabilities
The catalog spans two main categories: marketing blocks such as heroes, CTAs, pricing sections, testimonials, footers and navigation; and standard UI components such as buttons, inputs, modals, cards, tables, sliders and form controls. Components are community-contributed, and the platform lets users browse by type, popularity, featured collections and top authors, making it a source of both reusable code and design inspiration.
Who it's for
21st serves web developers, designers and product teams who want to build interfaces and marketing sites quickly using community-contributed components rather than building every element from scratch.