Thesys is going open source!

Introducing Generative UI

C1 by Thesys

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

Experience Generative UI in action

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

  • Travel Hidden Gems
  • Stocks to Watch
  • Football Legends
  • Global Street Food
  • Movie 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

  1. Change URL
  2. Integrate SDK
  3. Customize UI (Optional)

Code Example

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

C1 offers Enterprise-grade Security, Reliability, and Compliance

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.

Introducing C1 Artifacts API

Bring Slides and Reports to your AI App

Built for every use-case

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

AI-powered data visualizations

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

Frequently asked questions

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, C1 outputs structured UI components - such as forms, tables, charts, and layouts - that can be rendered directly using the C1 React SDK.

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.

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

C1 builds and shows the actual interface while the app is running, tailored to each user and situation.

Can I use C1 with any LLM?

Yes, C1 works with all leading LLMs out of the box, including models from Anthropic and OpenAI.

Can I bring my own UI components?

Yes, C1 lets you customize the UI to match your company’s design system.

Don't ship AI with legacy UI.

Build with C1.