21st
Infrastructure and UI building blocks for the agentic internet
About
21st.dev is the largest React component registry for AI applications, used by 2M developers (370K 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.
Build your own investing agent
GPAgent keeps YC listings public and neutral. Fund-specific scoring, notes, and workflow state live in each customer workspace.
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Status
Active
Stage
Early
Team Size
3
Regions
United States of America, America / Canada, Remote, Partly Remote