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Persona

Free

• Updated Jun 30, 2026, 03:13 PM

Persona is an open-source vanilla JavaScript library for building AI-powered chat interfaces on the web.

Use Cases ▼

Adding a customer support chatbot to a website

Building an AI copilot for a SaaS application

Creating a sales assistant widget for e-commerce

Embedding a documentation search and Q&A assistant

Developing an AI-driven onboarding or tutorial agent

Prototyping agentic web experiences with page control tools

What Problem It Solves ▼

Adding conversational AI interfaces to websites often requires heavy framework dependencies, complex integration, and risk of style conflicts. Persona solves this by providing a lightweight, framework-free chat UI library that works with any SSE backend, isolates styles via Shadow DOM, and offers flexible embedding options with minimal setup.

Key Features ▼

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Lightweight and framework-agnostic

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Easy integration via script tag or npm

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Shadow DOM prevents style conflicts

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Flexible UI modes (floating, docked, fullscreen)

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WebMCP support for agent-driven page actions

Overview

Persona is an open-source vanilla JavaScript library for building AI-powered chat interfaces on the web. It is framework-agnostic, requiring only a script tag or npm install to embed a customizable chat widget. The library supports three UI modes: floating launcher, docked copilot panel, and fullscreen assistant, all configurable through a simple init call. Persona streams messages from any backend that supports Server-Sent Events (SSE) and offers a pluggable parser system to adapt to different event shapes. It is WebMCP-native, enabling AI agents to directly interact with host page elements—such as forms, carts, or search—with built-in user approval flows. Shadow DOM rendering ensures that widget styles never conflict with host page styles, and a three-layer theming system (palette, semantic, component tokens) with dark mode and a live editor allows deep visual customization without forking. The library is distributed via npm (@runtypelabs/persona) and CDN, and provides pre-built integration examples for Express, Hono, SvelteKit, Next.js, and AI SDK backends, among others.