Overview
Persona.js and BaseRT are two open-source tools that address different parts of the AI stack. Persona.js is a lightweight, framework-free AI chat UI library that embeds into any website, from modern apps to static HTML. It is WebMCP-native, allowing your assistant to discover and execute tools exposed by the parent page. BaseRT, on the other hand, is the fastest LLM runtime on Apple Silicon, designed to run local models on your own device with a single command.
Feature Comparison
| Feature | Persona.js | BaseRT |
|---|---|---|
| Primary Purpose | Lightweight, framework-free AI chat UI library for embedding into any website | Fastest LLM runtime on Apple Silicon for running local models on-device |
| Installation | npm install @runtypelabs/persona or script tag via CDN | Single curl command: curl -LsSf https://basecompute.co/install.sh |
| Framework Dependency | Framework-free (Vanilla JS), works with any stack | Standalone runtime, no framework required |
| Backend Integration | Backend-agnostic, SSE streaming with pluggable parsers | Serves models locally, compatible with any agent via API |
| UI Modes | Floating launcher, docked copilot, fullscreen assistant | No UI; provides a model serving endpoint |
| Model Support | Not applicable (UI layer only) | Qwen3, Llama 3.1/3.2, Gemma 3/4, Mistral, Phi-3, Nomic BERT |
| Performance | Lightweight, Shadow DOM isolation, no style leaks | Up to 33% faster decode vs MLX/llama.cpp, up to 6.4x faster prefill |
| Agentic Capabilities | WebMCP-native: discovers and executes page tools with user approval | Serves models for coding agents; plugin available for pi agent |
| Theming | Three-layer token tree (palette, semantic, component) with dark mode and live editor | Not applicable |
| Target Platform | Any website (modern apps to static HTML) | Apple Silicon (M-series chips) |
Pricing
Persona.js: Open-source and free. The library itself is free to use. There is a hosted widget option via Runtype, which may have paid tiers for advanced features like server-side flow control.
BaseRT: Open-source and free. No pricing information is available on the website, suggesting it is fully free to use.
Pros and Cons
Persona.js
Pros:
- Framework-free, works with any tech stack including static HTML
- WebMCP-native for agentic page tool integration
- Multiple UI modes (floating, docked, fullscreen)
- Shadow DOM isolation prevents style conflicts
- Extensive theming system with dark mode
- Backend-agnostic with pluggable SSE parsers
Cons:
- Requires a backend SSE endpoint (not a standalone solution)
- Limited to chat/assistant UI; no model serving capabilities
- Relatively new library, smaller community
BaseRT
Pros:
- Fastest LLM runtime on Apple Silicon (up to 33% faster decode)
- Single command installation
- Supports a wide range of popular models
- Works offline, no data leaves the device
- Integrates with coding agents for local AI development
Cons:
- Only supports Apple Silicon (M-series) hardware
- No built-in UI; requires separate frontend or agent
- Limited to local model serving; no cloud integration
- Smaller model selection compared to some runtimes
Verdict
Persona.js and BaseRT serve complementary but distinct roles. Choose Persona.js if you need a lightweight, customizable chat UI that integrates with any website and leverages page tools via WebMCP. Choose BaseRT if you need the fastest local LLM inference on Apple Silicon for running models offline, especially for coding agents. For a complete on-device AI assistant, you could use both together: BaseRT serves the model, and Persona.js provides the frontend.