The production layer for shipping frontier AI agents inside your product - sandboxing, streaming, billing, UI, and observability out of the box.
tl;dr: We make it stupid easy to deploy frontier AI agents (Claude Code, Codex, others) inside your product. Define your agent in TypeScript, deploy with one command, ship it to your users.
Last year we built 21st.dev - a React component registry that 1.4M developers use to build UI for AI apps.
We also built our own AI agents from scratch to power the product. All custom. 15,000+ GitHub stars.
Then Claude Code arrived. We rewrote our agents on top of it - and they got better overnight than in months of our own work. That was a humbling moment.
But here's the thing - getting Claude Code into production was brutal. These agents aren't API calls. They're runtimes. They rely on bash, filesystem, persistent sandboxes. So you can't just run them on Vercel (timeouts, no fs). Then the questions start piling up. How do you sandbox securely? How do you make sure your env vars aren't stolen from the sandbox? How do you handle streaming? Billing? Observability? You end up building way more infrastructure than you planned for.
We spent 2 months deep in these problems. And then we realized - every team building on frontier agent SDKs is facing the exact same wall we just climbed over.
So we turned our infrastructure into a product.
The agent SDKs give you the brain. We give you everything else.
What you get out of the box:
How it works: you define your agent in code - custom tools, hooks like onFinish, sandbox configuration (which files, which CLI tools, which tokens). Then you deploy with our CLI. And you have a hosted agent you can manage via API. It's AI SDK compatible so you can just plug and play on the client side.
SDK supports React, Next.js, Node, and Python.
The best agents aren't being built from scratch anymore. They're being built on top of frontier agent runtimes from Anthropic, OpenAI, and others. But shipping them to real users? That's still a mess. The gap between "agent works on my machine" and "agent works for my customers" is enormous.
We already closed that gap for ourselves. Now we're the infra layer so you don't have to.
If you're building with frontier AI agents and hitting production walls - we want to hear about it. DM us on X (@serafimcloud, @sergeybunas) or email founders@21st.dev