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Company · Enterprise Software

21st

21st was founded in 2026 in San Francisco, USA by Serafim Korablev and Sergey Bunas. It is an Enterprise Software company.

UI building blocks for the agentic internet

Private Y Combinator · Winter 2026 Founded 2026 San Francisco USA Enterprise Software
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21st founders & co-founders

2
S
Serafim Korablev
CEO / co-founder
 S
Sergey Bunas
Founder

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