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21st Agents SDK

21st Agents SDK

SDK to add an Claude Code AI agent to your app

Website 21st.dev
Overview

What it is

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.

Intent

I need it when

Access reusable, production-ready UI components for common application patterns

The platform offers thousands of community-made React components (buttons, forms, pricing sections, AI chat interfaces, etc.) with Tailwind CSS styling, allowing developers to copy and remix components instead of building from scratch.

Integrate AI agents into web applications without managing complex infrastructure

21st Agents SDK provides developer tools and agent templates built specifically for the agentic internet, abstracting infrastructure complexity and enabling developers to focus on application logic and user experience.

Collaborate with other developers on open-source UI component libraries

The 21st community platform allows designers and developers to publish, discover, and remix high-quality React components, fostering collaboration and reducing duplication of effort across projects.

Build and deploy AI-powered applications quickly using modern web frameworks

21st Agents SDK enables developers to ship AI products faster by providing open-source tools, pre-built UI components, and agent templates designed for React and Next.js environments, reducing development time from concept to production.

Drop

Not a fit when

  • User needs a closed-source, proprietary agent framework with vendor lock-in guarantees
  • Organization requires commercial support contracts and SLAs for production AI agents
  • Project targets non-JavaScript/TypeScript environments or legacy backend systems
  • Team lacks React/Next.js expertise and cannot work with component-based UI patterns
  • Use case requires pre-built, domain-specific agent templates rather than a general SDK
Commercials

Pricing

Pricing not specified