21st
Community registry of React + Tailwind components in shadcn format — copy a prompt into Cursor/Claude, or npx shadcn add. Source lands in the repo. Not a package.
by 21st
21st is a catalog of UI from design engineers: animated heroes, shaders, cards, nav, full templates, shadcn themes. Aceternity, Magic UI, Origin UI, Kokonut, plus hundreds of authors. Same registry format as shadcn. You pick a block, paste the prompt (or the CLI command), and the agent writes files against your tokens. You edit the source. There is no 21st version to bump.
I keep it next to shadcn/ui here: that entry is the primitive kit this site already runs. 21st is where I grab motion, marketing blocks, and one-off effects without adding another aesthetic as a dependency. Browse free. Two copies a day without a membership. Site 21st.dev, source serafimcloud/21st.