Introducing Generative UI

Make AI apps respond withCharts Forms Charts Cards UI Forms

C1 by Thesys is an API middleware that augments LLMs to respond with interactive UI in realtime instead of text.

Try API for free

Try Playground →

Open demo

ChartsFormsCardsListsTablesSlidesReports

Trusted by the best AI-native teams

Website Website Website Website

Read Stories

Experience Generative UI in action

Type a prompt or pick a suggestion to interact with demos built with C1 API

Travel Hidden GemsStocks to WatchFootball LegendsGlobal Street FoodMovie Blockbusters

How C1 Works

C1 is an API layer on top of LLMs that builds adaptive UIs in real time.It turns responses from your model into live interfaces using our React SDK.

Integrate C1 in 2 easy steps

Step 1Change URLStep 2Integrate SDKStep 3Customize UI (Optional)

Read Documentation

Node.jsPython

const { OpenAI } = require('openai')

// Create OpenAI client with Thesys endpoint
const client = new OpenAI({
  apiKey: process.env.THESYS_API_KEY,
  baseURL: 'https://api.thesys.dev/v1/embed'
})

// Now use the client for your AI requests
const response = await client.chat.completions.create({
  model: '<model-name>',
  messages: [\
    { role: 'user', content: 'Hello, world!' }\
  ]
})

Built for AI-native teams

Ship AI experiences you can imagine - assistants, copilots, canvases, and more without any frontend overhead.

83% users find C1 responses more engaging compared to walls of text.

Read how text responses kill engagement →

Teams build AI frontend 10x faster and 80% cheaper, with C1.

Read how Fieldcamp reduced their time to market →

C1 offers Enterprise-grade Security, Reliability and Compliances

Zero data retention, GDPR, SOC2, ISO27001 compliant, Private deployment and more →

Built by Developers, for Developers

Zero overhead, fully flexible, giving developers total control.

Works with any AI stack

C1 is an OpenAI-compatible endpoint that plugs into any language, framework, or MCP.

Customizable and Responsive

C1 adapts to any form factor and can be styled to match your brand.

Supports all tool-calls

C1 connects to your data via tool calls, pulling results from databases, documents, & APIs.

Supports custom components

Bring your own React components with custom logic, styling, and interactions.

Configurable actions

Set up actions, callbacks, and workflows that C1 runs out of the box.

And much more...

From streaming to error handling, C1 has everything for production-ready UI.

Introducing C1 Artifacts API

Bring Slides and Reports to your AI App

Try it now

Know more →

Built for every use-case

Whether it’s data analytics, education, retail, or any other consumer application, Generative UI adapts to your needs.

AnalyticsE-commerceEdTechSearch

AI-powered data visualizations

Empower your AI agents to create interactive charts, graphs, and dashboards on the fly.

Read more

“We’ve been using C1 by Thesys to enhance our chat UI, and it’s been a game-changer. The component generation is top-notch, fast, clean, and incredibly intuitive.”

Jeel PatelCEO, Fieldcamp

Read full story

Frequently asked questions

Everything you need to know to get started.

What is C1 by Thesys?

C1 by Thesys is a LLM API that turns large language model (LLM) responses into live, adaptive user interfaces in real time.

Instead of returning plain text like traditional completion endpoints, C1 outputs structured UI components - such as forms, tables, charts, and layouts - that can be rendered directly using the C1 React SDK.

It supports multiple LLMs like OpenAI, Anthropic, & more, works out of the box or with your custom design system, and is built for fast, secure, and real-time rendering of dynamic interfaces.

With C1, developers can build intelligent, context-aware frontends for AI-powered apps - without hardcoding the UI for every possible user query or state.

Who is Generative UI for?

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.

How is this different from vibe-coding tools like Lovable or Bolt?

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.

Can I use C1 with any LLM?

Yes, C1 works with all leading LLMs out of the box, including models from Anthropic and OpenAI. We're continuously adding more to give you maximum flexibility to build, test, and scale without locking into a single provider.

Can I bring my own UI components?

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.

Don't ship AI with legacy UI.

Build with C1.

npx create-c1-app

Try Playground