21st.dev
UI components and AI agent infrastructure
21st.dev is a platform providing UI components and infrastructure for building AI-powered applications, including a large registry of open-source React components and an Agents SDK for deploying AI coding agents with built-in sandboxing, streaming, and observability. The company also develops 1Code, an open-source desktop client for orchestrating coding agents such as Claude Code and OpenAI Codex.
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Key People
Core OSS Projects
MCP server for AI-powered frontend development in Cursor, Windsurf, and Cline
The fastest way to add an AI agent to your app — runtimes, sandboxed execution, streaming, drop-in React components
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AI AgentsIndustries
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