21st
21st (21st.dev) operates a curated React component marketplace and AI agent infrastructure platform serving 1.4 million developers, offering Magic AI UI generation, the Agents SDK with sandboxed execution and credential vaults, and community-driven templates for AI-assisted frontend development.
- Company typePrivate
- Founded2024
- HeadquartersSan Francisco, United States
- Headcount1–10
- GTM typeB2B and B2C
- OfferingSoftware
What 21st does
21st (21st.dev) operates a developer-focused platform centered on a curated marketplace of thousands of React UI components and templates styled with Tailwind CSS, serving a community of approximately 1.4 million developers. The company positions itself as the alternative to generic AI-generated UI design, emphasizing community curation and craft over machine-generated output. Beyond the component registry, the platform includes Magic, an AI UI generator that produces multiple styled React component variations from text descriptions and distributes via an MCP server for integration with Cursor, Windsurf, and VS Code + Cline.
The company has expanded into managed AI agent infrastructure with its Agents SDK, which provides sandboxed execution via E2B microVMs with gVisor isolation, Credential Vaults for secure API key injection (where the LLM never sees secret bytes), SSE streaming compatible with the Vercel AI SDK, and a drop-in React chat UI built on the open-source Agent Elements library of 25 shadcn/ui components. The architecture is TypeScript-first with server SDKs for Node.js, Python, and Go, and supports Claude Code and OpenAI Codex as default agent runtimes. Supporting products include Component Libraries for team-scoped private publishing, an Agent Registry for sharing Anthropic Managed Agent configurations, and Creator Studio for publishing workflows.
Revenue is generated through four streams: usage-based pricing on the Agents SDK, pay-what-you-want membership starting at $5 per month, Magic AI subscriptions at $20 per month (Pro) and $100 per month (Max), and a custom Scale enterprise plan offering on-premise VPC deployment, SSO/Okta, audit logs, and dedicated support. The go-to-market is community-led and product-led, leveraging the free component marketplace as a top-of-funnel acquisition channel, MCP-based distribution into AI coding IDEs, and Y Combinator credibility. The company is privately held, headquartered in San Francisco, employs 1-10 people, and was founded in 2024 with a $500,000 seed round led by Y Combinator in March 2026.
21st firmographics
Firmographics- Name
- 21st
- Legal name
- 21st
- Website
- https://21st.dev
- Company type
- Private
- Founded year
- 2024
- Operating status
- Operating
- Headcount range
- 1–10 employees
- Short description
- 21st (21st.dev) operates a curated React component marketplace and AI agent infrastructure platform serving 1.4 million developers, offering Magic AI UI generation, the Agents SDK with sandboxed execution and credential vaults, and community-driven templates for AI-assisted frontend development.
- Ownership category
- akta.pro rank
21st industry classification
Industry- Product category
- Developer Tools & AI Agent Infrastructure
- NAICS
- Software Publishers (5132), Software Publishers (513210)
- SIC
- Services-Prepackaged Software (7372), Services-Computer Programming Services (7371)
- akta.pro primary industry
- AI Application Enablement Platforms (Copilot/Agent Frameworks, SDKs) (HDAEANAJ)
- akta.pro secondary industries
- LLMOps & Generative AI Platforms (Prompt/Agent Orchestration, RAG) (HDAEANAD), Developer Experience Platforms for Enterprise (IDEs, CI/CD, Dev Portals) (HDAEAKAI)
Keywords
Where 21st is headquartered
LocationHeadquarters
- HQ city
- San Francisco
- HQ country
- United States
- HQ region
- North America
Markets served
21st business model
Business model- GTM type
- B2B and B2C
- Offering type
- Software
- Cost components
- Personnel, Technology or R&D, Infrastructure, Marketing or Sales, Operations
Revenue model
- Agents SDK Usage-Based Revenue: Managed agent infrastructure concentrated revenue through usage-based pricing on the SDK. The flywheel model drives developer acquisition through the free component registry while the SDK concentrates revenue through usage-based pricing.
- 21st Membership (Pay-What-You-Want): Membership unlocks unlimited component copies, prompts, code, demos, and registry installs. Priced at pay-what-you-want starting from $5/month. For ~95% of users, 2 free component copies per day remains free. Membership supports the curation and moderation work.
- Magic AI Pro/Max Subscriptions: Magic product has a Free tier (100 credits/month) and two paid tiers: Pro at $20/month (400 credits/month, clone site feature, priority support) and Max at $100/month (2000 credits/month, early access to new features). Annual billing offers 20% discount.
- Scale/Custom Enterprise Plan: Custom enterprise tier for teams running agents on their own infrastructure, including on-premise deployment in VPC, SSO & Okta (SAML, OIDC), immutable audit logs, budget caps per agent, full run replay with cost breakdown, and custom sandbox specs.
Pricing tiers
| Model | Billing | Price |
|---|---|---|
| Freemium | Monthly | Free tier with 100 credits/month for Magic AI UI generation |
| Subscription | Monthly | Pro subscription at $20/month for professional developers |
| Subscription | Monthly | Max subscription at $100/month for power users and teams |
| Subscription | Monthly | Pay-what-you-want membership starting at $5/month |
| Usage-based | Pay-as-you-go | Usage-based plan for developers shipping their first agents |
| Subscription | Multi-year contract | Custom enterprise plan with on-premise deployment and dedicated support |
Go-to-market motion3 records
Distribution channels5 records
Marketing channels8 records
21st product offering
Product offeringCore offering
21st operates a dual-product platform: a curated community marketplace of thousands of crafted React UI components and templates (built with Tailwind CSS and Next.js compatibility) serving 1.4 million frontend developers, paired with managed AI agent infrastructure via its Agents SDK that provides sandboxed execution (E2B microVMs with gVisor), credential proxying, SSE streaming, and drop-in React chat UI for teams deploying production AI agents.
Product overview
21st (21st.dev) operates a dual-product platform centered on fighting AI slop in UI design. The core offering consists of the 21st Component Registry — a curated marketplace of thousands of React components and templates styled with Tailwind CSS — paired with Magic, an AI-powered UI generator that produces multiple styled component variations from text descriptions via MCP server or web interface. The company has expanded into managed agent infrastructure with its Agents SDK, which handles sandboxed E2B runtimes (Claude Code/OpenAI Codex), credential injection via Credential Vaults, streaming, and drop-in React chat UI. Supporting products include Component Libraries for team-scoped private component publishing, the Agent Registry for Anthropic Managed Agent configuration sharing, the 21st MCP Server exposing Inspiration Search and SVG Icon Search tools to IDEs, and Agent Elements — 25 open-source shadcn/ui React components built specifically for agent interfaces. Creator Studio provides the web UI for publishing, while 21st Membership offers unlimited downloads beyond the free daily limit. The platform is Y Combinator-backed.
Differentiator
Problem solved
Functional benefit
Brands
- Agent Elements: Open-source collection of 25 chat and agent UI components built on shadcn/ui. Includes AgentChat, tool cards (BashTool, EditTool, SearchTool, PlanTool, etc.), streaming states, and input controls. Designed for production agent UIs with diffed edits, plan approvals, and tool visualizations.
- Magic Chat
- Magic MCP
- Component Libraries
- Credential Vaults
- Agents SDK
- Agent Registry
Products and services
- 21st Component Registry A curated community marketplace of crafted React UI components and templates styled with Tailwind CSS and Next.js compatibility. Serves 1.4 million frontend developers across marketing blocks (heroes, features, footers, pricing), UI elements (buttons, inputs, cards), and full templates (landing pages, dashboards, SaaS).
- Magic (Magic Chat) AI-powered UI generator that produces multiple styled React/TypeScript component variations from a single text description. Accessible via MCP server in Cursor, Windsurf, VS Code + Cline, or via web interface. Includes SVGL integration for brand SVG icons and logos. Pricing: Free (100 credits/month), Pro ($20/month, 400 credits), Max ($100/month, 2000 credits).
- 21st Agents SDK Infrastructure SDK for shipping AI agents to production. Provides E2B microVM sandboxed runtimes with gVisor isolation, credential management, JWT-based token exchange auth, SSE streaming (Vercel AI SDK compatible), React chat UI components, and an observability dashboard. TypeScript-first with server SDKs for Node.js, Python, and Go. Usage-based pricing with a Scale tier for enterprise on-premise deployment.
- Agent Elements Open-source collection of 25 shadcn/ui React components purpose-built for modern AI agent interfaces. Includes AgentChat, MessageList, Markdown, BashTool, EditTool, PlanTool, SubagentTool, QuestionTool, ThinkingTool, SearchTool, TodoTool, and McpTool. Ships with its own Claude Code skill. Installable one component at a time with no runtime dependency on 21st.
- Agent Registry Community marketplace for Anthropic Managed Agent configurations. Enables publishing agent YAML/JSON configs with AI-generated descriptions and READMEs, browsing 9 categories (Coding, Data Analysis, DevOps, Content, Research, Customer Support, Workflow, Monitoring, Multi-Agent), filtering by MCP server, and exporting configs for direct Anthropic Console import.
- 21st MCP Server Model Context Protocol server that exposes 21st tools — Inspiration Search (semantic search across thousands of components), SVG Icon Search (svgl-powered brand icon lookup), and Magic Generate (5 polished UI variants) — directly to AI assistants in Cursor, Windsurf, VS Code + Cline, and any MCP-compatible IDE.
- Creator Studio Web-based interface for publishing React components to the 21st community registry or to private team libraries. Supports component uploads, metadata editing, visibility controls (public/unlisted/private), and submission for catalog review. Also accessible via CLI for CI/CD and agent-driven publishing.
Quantifiable outcome
- 21st has 1.4 million developers using its component registry, creating a large developer acquisition funnel for the agent infrastructure product
- +2 more outcomes
Companies that use 21st
Customer profileSegments3 records
Ideal customer profiles3 records
21st technology and API
TechnologyTechnology focussed Yes
API detail
- Has API
- Yes
- API docs
- API detail
Core technology
AI maturity
App detail
Integration18 records
AI capability11 records
Feature9 records
21st partnerships and signals
Strategic signalPartnerships
Six partnerships are on record, tiered core and minor.
- E2Bcore21st's Agents SDK provisions E2B sandboxes on demand for every agent session. E2B provides microVM-based sandboxed execution environments with gVisor container isolation. E2B is the core infrastructure provider for the agent runtime.
- AnthropiccoreThe Agents SDK uses Claude Code (Anthropic's agentic coding runtime) as the default agent runtime. Claude Code provides file/terminal tools, web search, and reasoning capabilities inside the E2B sandbox. Anthropic's Claude Sonnet 4.6 is the default model.
- shadcn/uicoreAgent Elements is built on top of shadcn/ui — an open-source component collection that works with any AI SDK. Components are installed via npx shadcn@latest add. The shadcn model (own the code, not a package) aligns with 21st's philosophy.
- Vercel AI SDKcore21st's streaming is SSE-based and AI SDK-compatible. The AgentChat component is designed around UIMessage and ChatStatus from the Vercel AI SDK, plugging directly into useChat. Both 21st SDK and Agent Elements are Vercel AI SDK compatible.
- MCP (Model Context Protocol)core21st supports the full MCP protocol. MCP servers run on the sandbox host managed by the Sandbox Manager, with the agent container accessing them through the trusted control layer. 21st's Magic product is distributed as an MCP server. Agent Elements includes an McpTool component.
- Cursor, Windsurf, Cline (IDE Partners)minorMagic MCP server is positioned as working with Cursor (AI-first code editor), Windsurf (Agentic IDE), and VS Code + Cline (open source AI agent). IDE partnerships enable in-editor distribution of the Magic tool.
Scale indicators2 records
Recent moves6 records
Expansion highlights5 records
21st competitors and assessment
Company assessmentBroad incumbents
- Cursor: AI-first code editor that 21st's Magic MCP server integrates with. A larger incumbent that could itself ship deeper UI/component generation, making it both a distribution channel and a potential competitor to Magic.
- Vercel: Cloud platform for Next.js and the publisher of the Vercel AI SDK that 21st integrates with. Competes at the developer-platform layer with broader infrastructure, hosting, and AI tooling offerings that include v0 for AI UI generation — a direct overlap with Magic.
- Replit Agent: AI agent built into the Replit cloud IDE that writes and deploys full applications. Competes with the Agents SDK in the 'managed agent infrastructure' category and overlaps on serving developer-builder use cases.
Direct peers
- Lovable: AI app builder that generates full-stack React/Next.js applications from prompts. Competes with Magic on AI UI generation and overlaps with 21st's design-engineer target customer.
- shadcn: Open-source React component collection distributed via the shadcn CLI that 21st's Agent Elements is built on top of and complements. Direct overlap in the curated React component space with a similar 'own the code' distribution model.
- LangChain: Framework and platform for building LLM applications and agents. Competes with 21st's Agents SDK in the agent-orchestration and infrastructure category, with broader language coverage but a less curated developer-experience focus.
- Magic Patterns: AI-powered UI design tool that generates production React components from prompts. Direct competitor to 21st's Magic product in the AI UI generation category, targeting similar frontend developers.
- Builder.io: Visual development platform with AI-powered UI generation and a React component ecosystem. Competes with 21st across the component marketplace and AI UI generation surfaces, especially for design-engineer workflows.
- Bolt.new: StackBlitz's AI-driven browser-based app builder for full-stack web apps. Competes with Magic for AI UI generation and competes with 21st's component marketplace for developer mindshare on AI-assisted frontend work.
Others
- E2B: Provider of the sandboxed microVM infrastructure that 21st's Agents SDK is built on. An enabling partner and infrastructure supplier rather than a direct competitor, but a vendor whose pricing or terms directly affect 21st's unit economics.
Market position
Strengths4 records
Weaknesses4 records
Competitive moat4 records
Key risks5 records
Key highlights5 records
Customer concentration
21st social profiles
Digital presence21st financial estimates
Financial estimateRevenue estimate
Valuation estimate
21st leadership team
Management profileNumber of profiles
Profiles9 records
21st funding detail
Funding detailFunding overview
Funding rounds3 records
Investors5 records
Funding detail is available on the Subscription and Enterprise plan.Contact sales →
21st M&A and investment
M&A and investmentM&A
Investments
M&A and investment is available on the Subscription and Enterprise plan.Contact sales →
Frequently asked questions about 21st
What does 21st do?
21st operates a dual-product platform: a curated community marketplace of thousands of crafted React UI components and templates (built with Tailwind CSS and Next.js compatibility) serving 1.4 million frontend developers, paired with managed AI agent infrastructure via its Agents SDK that provides sandboxed execution (E2B microVMs with gVisor), credential proxying, SSE streaming, and drop-in React chat UI for teams deploying production AI agents.
Is 21st a public or private company?
21st is a private company. It is classified as venture growth investor backed and is currently operating.
When was 21st founded?
21st was founded in 2024. It employs 1 to 10 people.
Where is 21st based?
21st is headquartered in San Francisco, United States, in the North America region.
How does 21st make money?
Four revenue lines are on record. Agents SDK Usage-Based Revenue is the primary driver. The others are 21st Membership (Pay-What-You-Want), magic AI Pro/Max Subscriptions and scale/Custom Enterprise Plan.
Who are 21st's main competitors?
Broad incumbents on record are Cursor, Vercel and Replit Agent. Direct peers are Lovable, shadcn, LangChain, Magic Patterns, Builder.io and Bolt.new. E2B is listed as an others.
Does 21st have an API?
Yes. 21st provides a TypeScript-based Agents SDK for defining, deploying, and managing AI agents. Server-side SDKs are available for Node.js, Python, and Go. The platform uses Server-Sent Events (SSE) for real-time streaming, compatible with the Vercel AI SDK. Authentication uses API key to JWT token exchange (an_sk_ prefix). The platform also offers an MCP (Model Context Protocol) server integration, with the Inspiration Search and SVG Icon Search tools available as MCP tools. Agent configurations can be exported in YAML, JSON, TypeScript, and Python formats. Developer documentation is at 21st.dev/agents/docs.
What industry is 21st in?
21st's product category is Developer Tools & AI Agent Infrastructure. Its primary akta.pro industry code is HDAEANAJ, AI Application Enablement Platforms (Copilot/Agent Frameworks, SDKs), with a secondary code of HDAEANAD, LLMOps & Generative AI Platforms (Prompt/Agent Orchestration, RAG). Its NAICS code is 5132 and its SIC code is 7372.