What is 21st?
21st: Infrastructure and UI building blocks for the agentic internet. Headquartered in San Francisco, CA, United States. Current operating status: active.
21st: Infrastructure and UI building blocks for the agentic internet. Headquartered in San Francisco, CA, United States. Current operating status: active.
Oomira checked this YC company record against source evidence and keeps the current facts, observed dates, and provenance visible before the interactive app loads.
21st: Infrastructure and UI building blocks for the agentic internet. Headquartered in San Francisco, CA, United States. Current operating status: active.
21st is currently marked active, in B2B, based in San Francisco, CA, United States, with hiring marked no.
Oomira found 4 changes for 21st: external name. The old value, newer value, observation date, and source trail are preserved together.
The frozen capsule includes observations from 2026. Dates stay attached to the facts instead of being flattened into a timeless profile.
This page exposes the company answer, changes, dates, and sources as HTML so people and crawlers can read the audit without operating the app.
1code by 21st.dev -> 21st
2026-06-12 · yc-oss record id 31123: field "former_names" includes "1code by 21st.dev"
21st.dev -> 21st
2026-06-12 · yc-oss record id 31123: field "former_names" includes "21st.dev"
ex: 21st.dev -> 21st
2026-06-12 · yc-oss record id 31123: field "former_names" includes "ex: 21st.dev"
1code -> 21st
2026-06-13 · YC directory former_names includes "1code"
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