C1 by Thesys is an API middleware designed to enhance large language models (LLMs) by enabling them to generate interactive user interfaces in real time. Rather than simply returning text responses, C1 transforms these responses into live UI components like forms, tables, and charts, which can be rendered using the C1 React SDK. This allows developers to create dynamic, context-aware applications without hardcoding responses for every possible user interaction. Integrating C1 involves just two steps, using a client setup that connects to Thesys’ API endpoint. This straightforward process allows developers to leverage the capabilities of various LLMs, including those from OpenAI and Anthropic, without being tied to a single provider. The platform is built for AI-native teams, supporting rapid development of intelligent interfaces tailored to specific tasks and user behaviors. C1 differentiates itself from tools like Lovable or Bolt. While those tools focus on assisting with code generation for UI design, C1 actively builds and displays the interface as the application runs. It adapts to changes in logic, state, and user interactions in real time. Developers can also customize the UI to align with their design systems, utilizing features from Crayon's UI library for themes and components, ensuring flexibility in visual presentation.