Persona

Persona is a lightweight, open-source, framework-free AI chat UI library built by Runtype. It lets developers embed a fully themeable AI chat widget or a full-screen copilot experience into any website or static HTML page, without locking you into a particular frontend framework or stack.

The library is backend-agnostic and WebMCP-native. This means AI assistants can automatically discover and safely execute tools exposed directly by the parent page code, such as searches, carts, bookings, and forms, with built-in user approval so visitors stay in control of every action.

On the technical side, Persona supports SSE streaming and agent loops for smooth, responsive conversations. Style isolation is handled through Shadow DOM to prevent CSS leaks in either direction, while voice input and output make interactions more accessible. An extensive theme editor is included, so matching the widget to your brand takes minutes rather than days.