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.
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Imagine seamlessly integrating the power of a sophisticated Claude Code AI agent directly into your existing application. That is precisely what the 5. 21st Agents SDK is designed to deliver. We understand that developers today are looking for more than just raw APIs; you need robust, ready-to-deploy building blocks that handle the complexity of agent infrastructure so you can focus purely on user experience and core functionality. This SDK provides everything necessary to embed advanced AI capabilities, specifically leveraging the Claude model, right where your users need it most. It’s not just about adding a feature; it’s about instantly upgrading your application into an intelligent platform capable of complex reasoning, coding assistance, or advanced task execution, all managed through a streamlined developer kit. We’ve engineered this solution to drastically cut down on integration time while maximizing performance and reliability, drawing on the collective experience of 1.4 million developers who trust the 21st.dev ecosystem for their AI projects.
What truly sets the 21st Agents SDK apart is the comprehensive nature of the toolkit. Forget wrestling with separate libraries for state management, logging, or connecting to external tools. This SDK bundles essential features like built-in UI components, pre-configured agent templates, persistent memory modules, and critical observability tools right out of the box. This means you get a fully functional, enterprise-ready AI agent experience without needing to build the scaffolding from scratch. Whether you are looking to implement an in-app coding assistant, a sophisticated customer support bot, or a powerful data analysis tool, the SDK manages the heavy lifting of infrastructure and deployment. It ensures your agent remains connected, remembers context across sessions, and provides you with the necessary insights to monitor its performance and iterate quickly, giving you the speed and stability required in today's fast-paced development environment.