21st.dev is an open source community registry of React UI components, enabling design engineers to ship polished user interfaces more efficiently. Inspired by shadcn/ui, it offers ready-to-use React Tailwind components that can be installed with a single command using npx shadcn. The platform provides a comprehensive collection of UI elements, including accordions, alerts, avatars, badges, buttons, calendars, cards, carousels, checkboxes, dialogs, dropdowns, forms, icons, inputs, menus, notifications, pagination, popovers, radio groups, selects, sidebars, sliders, tables, tabs, tags, text areas, toasts, toggles, and tooltips. Additionally, it features landing page components such as announcements, backgrounds, borders, call-to-actions, client sections, comparisons, docks, features, footers, hero sections, image galleries, maps, navigation menus, pricing tables, scroll areas, testimonials, text blocks, and video sections.