Generative UI is here

Introducing C1

The Generative UI API for building engaging AI products.
Boring Agent
C1 Agent
Generative UI makes conversations truly engaging.
It understands intent, senses context, respects choices.
With every interaction, the UI redesigns itself
so your users feel understood, not just responded to.
Join 400+ teams building Generative UI experiences with Thesys
Without an engaging interface,
even the smartest AI agents fall flat.Building UI for AI is harder than it should be
card
Weak engagementUsers expect more than text only conversations.
card
Mediocre designHardcoded UI doesn’t adapt to user input or context.
card
Slow velocityManually developing User Interface for AI slows teams down.
Introducing C1 C1 uses Generative UI to bring AI conversations to life - effortlessly.
card
Dynamic & engagingVisually rich UI powered with forms, charts, images and more.
card
Insanely fast executionGuide UI generation with system prompts.
Banner Card Image
Thinks like a designer
in real-timeC1 responds to user input and builds consistent and intuitive UI in real time.
No need to wait for the next design iteration.
card
SecureThesys never stores your data and adheres to industry security standards.
card
EffortlessIntegrate in minutes, with just two snippets of code.
card
UniversalC1 integrates seamlessly with any language, framework and MCP server.
Try ChatWe built an AI chatbot to demonstrate the Generative UI power of C1. Try it now.
Cast of Harry Potter
Celestial objects
Compare Different Diet Plans
Best workout routine
Best vacation destination
Frontend Layers
Automate your frontend.
Building a new agent or improving an existing one?Integrate C1 in 3 easy steps
ResourcesEnhance your product with C1
AI-powered shopping experiencesE-commerce businesses can deliver personalized shopping experiences, 24/7 support, and seamless transactions. All driven by the Generative UI capabilities of C1.
E-commerce demo
FAQsCheck out our FAQs for quick answers. Need more help?
Contact us anytime.

C1 by Thesys is a Generative UI API that lets you build AI-powered applications with interfaces that generate themselves - based on user input, context, or intent - instead of being hardcoded.

It's an OpenAI-compatible endpoint that returns structured UI components like forms, visualizations and layouts instead of markdown. The output is then parsed by the React SDK to create the UI.

You prompt it like a chat completion API-and it responds with live, usable UI.

Generative UI is for teams building AI-native software-agents, copilots, and tools-where use cases evolve fast, and static UIs fall short.

  • Adapts to logic, state, and user behavior
  • LLMs shape both output and interaction

Perfect for devs, product teams, and builders creating dynamic, task-specific interfaces.

Tools like Lovable or Bolt help you design UI before your app goes live-they turn prompts into mockups or code.

C1 by Thesys is different: it builds and shows the actual interface while the app is running, tailored to each user and situation. Think of it this way:

  • Tools like Lovable or Bolt are coding assistants that help write the code that powers the UI.
  • C1 is the UI - live, flexible, and ready when users need it.

Yes, we currently support Anthropic models and are planning to add support for more LLMs, including OpenAI, soon to give developers even more flexibility.

Yes, C1 lets you customize the UI to match your companys design system.

It's built on top of Crayon's UI library, so any customization supported by Crayon - like themes, tokens, or components - works out of the box.