ElevenLabs UI is an open-source library designed to facilitate the development of multimodal agents by offering customizable React components that integrate with the ElevenLabs Agents and Audio SDKs. Built on the shadcn/ui framework, it allows developers to manipulate UI elements like waveforms and orbs, and includes examples such as a voice dictation component and a multimodal chat interface with built-in state management. Developers can easily access these components using the @elevenlabs/agents-cli command, enabling the rapid building of advanced agent and audio interfaces. The product demonstration includes practical applications like ElevenLabs' Agent Workflows, which is a visual editor for designing conversation flows, and customer success stories such as Le Walk, which utilizes ElevenLabs for digital tour guides.