21st
UI building blocks for the agentic internet
21st is a 21st.dev is a component library and AI-assisted UI workflow platform for finding, copying, and building polished React/Tailwind UI. Its pricing page lists plans for individuals and teams, including a free browse tier plus paid Builder, Builder + AI, and Team options. AI agent company selling to Individuals, teams, agencies, and businesses building with UI components and AI-assisted workflows. Latest disclosed round: Last known: Pre-seed (2025) ($500,000, 2025-03-03). About 5 employees, -28.6% over 6 months. 3,837 followers on X.
Product
- Agent type
- 21st.dev is a component library and AI-assisted UI workflow platform for finding, copying, and building polished React/Tailwind UI. Its pricing page lists plans for individuals and teams, including a free browse tier plus paid Builder, Builder + AI, and Team options.
- Primary buyer
- Individuals, teams, agencies, and businesses building with UI components and AI-assisted workflows
- Integrations
- —
- MCP support
- —
- HQ
- San Francisco, California, US
- Founded
- 2025
- Profile ↗
Funding
- Date
- Mar 3, 2025
- Leads
- —
- Source
- Announcement ↗
- Investors
- Aal Vc; First Peak Ventures; Hustle Fund; Pioneer Fund; Sahin Boydas; Trac; Y Combinator
Hiring
- Employees
- 5
- Growth 3m / 6m
- — / -28.6%
- Open roles (sample)
- —
- X mentions this week
- —
- X handle
- @21st_dev
Top launch posts
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Recent news
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Sources
- Headcount
- Clay (LinkedIn)
- Open jobs
- —
- Traffic
- Clay (web traffic)
- Pricing
- https://21st.dev/pricing
- X metrics
- https://x.com/21st_dev
- X handle (homepage-verified)
- https://www.ycombinator.com/companies/21st | https://21st.dev
- Clay enrichment
- Clay enrichment 2026-11-04
- seed_type
- YC directory
- funding_status
- Last known (aggregator source)
- funding_source_type
- aggregator
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About 21st
What does 21st do?+
UI building blocks for the agentic internet
How much has 21st raised most recently?+
Last known: Pre-seed (2025) of $500K on Mar 3, 2025.
How many employees does 21st have?+
About 5 (3-month growth —).
How is 21st priced?+
Subscription, starting at $6/month billed yearly.
Cite this data
21st profile. Agent Market Map, The GTM Engineering Newsletter. Last verified Nov 4, 2026. https://agentmarketmaps.com/company/21st