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21st

Winter 2026Active

UI building blocks for the agentic internet

Save
21st logo

21st

Winter 2026Active

UI building blocks for the agentic internet

Save
Company details

21st.dev is the largest React component registry for AI applications, used by 2M developers We provide the building blocks to create agent-powered apps: UI components, agent templates.

Location
San Francisco, CA, USA
Founded
Unknown
YC Directory Page21st.dev
Founders
  • SK
    Serafim Korablev
    CEO / co-founder
    X / TwitterLinkedIn
  • SB
    Sergey Bunas
    Founder
    X / TwitterLinkedIn

21st.dev is the largest React component registry for AI applications, used by 2M developers We provide the building blocks to create agent-powered apps: UI components, agent templates.

Location
San Francisco, CA, USA
Founded
Unknown
YC Directory Page21st.dev
Founders
  • SK
    Serafim Korablev
    CEO / co-founder
    X / TwitterLinkedIn
  • SB
    Sergey Bunas
    Founder
    X / TwitterLinkedIn
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