21st

21st

Infra and UI building blocks for the agentic internet

5.0
6 reviews

2.6K followers

21st.dev is the largest React component registry for AI applications, used by 1.4M developers (200K MAU). We provide the building blocks to create AI agents and agent-powered apps: UI components, agent templates, and an SDK with built-in UI, tools, memory, observability, and managed infrastructure.

21st

Launch date
21st Agents SDK
21st Agents SDKSDK to add an Claude Code AI agent to your app

Launched on March 7th, 2026

21st.dev 2.0Create, remix and share UI components with AI

Launched on July 8th, 2025

21st.dev
21st.devGithub + Pinterest to make your AI websites look beautiful

Launched on January 11th, 2025