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21st.dev

marketplacekey

The largest community marketplace of shadcn-style React components (12k+) — heroes, buttons, cards, AI chats, pricing, dashboards — with an MCP for agent search.

$npx shadcn@latest add "https://21st.dev/r/<author>/<slug>?api_key=$API_KEY_21ST"

21st.dev

Use it for: breadth. When Aceternity/our registry doesn't have the thing (a specific dashboard widget, file tree, odd input), search 21st.

Setup

  1. Create a free account → API key at https://21st.dev/mcp, export API_KEY_21ST.
  2. MCP for search: npx @21st-dev/cli@latest init --client claude (endpoint https://21st.dev/api/mcp).
  3. Install an item: npx shadcn@latest add "https://21st.dev/r/<author>/<slug>?api_key=$API_KEY_21ST".

Our preset (presets/components.registries.json) also defines @21st with the key passed as a header, so npx shadcn@latest add @21st/<author>/<slug> may work — fall back to the URL form if not.

Machine access

/llms.txt, /openapi.json, /.well-known/skills/index.json. Page URLs: https://21st.dev/@<author>/components/<slug>; categories: /community/components/s/<tag>.

Gotchas

  • Quality varies wildly — prefer items with many installs/likes, read the code before shipping.
  • Licences are per author; anything without a clear permissive licence stays out of @oc.
  • Code retrieval through the MCP is a paid feature; search is free.