MCP App framework for ChatGPT Apps. MCP App framework for Claude Apps.
sunpeak is an open-source MCP App framework and ChatGPT App framework that helps developers build, test, and ship MCP Apps embedded in ChatGPT, Claude, and other AI hosts.
pnpm add -g sunpeak && sunpeak new
What is sunpeak?
MCP Apps are interactive UIs that run inside AI hosts like ChatGPT and Claude via the Model Context Protocol. ChatGPT Apps are MCP Apps rendered inside ChatGPT—sunpeak provides the complete MCP App framework for both.
sunpeak is an open-source (MIT) MCP App framework and ChatGPT App framework. Build, test, and ship MCP Apps embedded in ChatGPT, Claude, and other AI hosts from one codebase.
Local ChatGPT App Simulator
Test MCP Apps locally without a paid ChatGPT account
ChatGPT & MCP App Testing
Local and automated testing with Vitest and Playwright
MCP Dev Server
Hot reloading MCP server with mock data
MCP App UI Components
Pre-built UI components for MCP Apps
MCP App APIs
20+ typed React hooks for the MCP App runtime
CLI Tools
Scaffold, build, test, and ship apps
Test MCP Apps & ChatGPT Apps Locally
Use the sunpeak simulator for MCP App testing and ChatGPT App testing locally and in CI/CD. The simulator replicates the MCP App runtime for deterministic and automatic UI testing.
Build MCP Apps for ChatGPT & Claude
Use the sunpeak MCP App framework to build interactive apps for ChatGPT, Claude, and other AI hosts. Think Next.js for MCP Apps.
// src/resources/review-resource.tsx
import { useToolData } from 'sunpeak';
import type { ResourceConfig } from 'sunpeak';
export const resource: ResourceConfig = {
name: 'review',
description: 'Visualize and review a code change',
_meta: { ui: { csp: { resourceDomains: ['https://cdn.openai.com'] } } },
};
export function ReviewResource() {
const { output: data } = useToolData<unknown, { title: string }>();
return <h1>Review: {data?.title}</h1>;
}MCP App Framework Features:
- Local ChatGPT App simulator for ChatGPT App development
- Pre-built MCP App UI components following ChatGPT design guidelines
- Cross-platform MCP App development for ChatGPT, Claude, and more
- MCP dev server with hot module replacement for rapid iteration
- ChatGPT App testing and MCP App testing with Vitest and Playwright
Built for MCP Apps, ChatGPT Apps, and Claude Apps
Build MCP Apps
Create interactive MCP Apps for ChatGPT and Claude with pre-built UI components and typed APIs.
Build ChatGPT Apps
Build ChatGPT Apps with interactive UIs that run inside ChatGPT conversations.
Test MCP Apps Locally
Test MCP Apps and ChatGPT Apps locally with the sunpeak simulator. No paid ChatGPT account required.
Run Tests in CI
Run MCP App testing and ChatGPT App testing in CI with deterministic UI states and Playwright.
Build Once, Deploy Anywhere
Build once and deploy across MCP-compatible AI hosts like ChatGPT and Claude.
Ship MCP Apps
Deploy to your MCP server or use the sunpeak Resource Repository for hosted MCP App delivery.
Ship MCP Apps
Use the sunpeak CLI and Resource Repository to decouple your MCP App from your MCP server. Ship MCP Apps for ChatGPT and Claude independently.
Generic MCP Servers
Keep servers client-agnostic
Independent Lifecycles
Separate UI and server versioning
Team Collaboration
Frontend and backend work independently
Independent Deploys
Update UI without server redeploy
Popular Docs
Frequently Asked Questions
Key Facts
- Product
- sunpeak
- Category
- MCP App framework & ChatGPT App framework
- License
- MIT (open source)
- Package
- sunpeak (npm)
- Includes
- Local ChatGPT App simulator, MCP dev server, UI components, testing (Vitest, Playwright), CLI
What is an MCP App?
An MCP App is an interactive application built on the Model Context Protocol (MCP) that runs inside AI hosts like ChatGPT and Claude. MCP Apps consist of Resources (UI views) and Tools (API actions), enabling rich UI experiences like forms, charts, and interactive components directly in chat. ChatGPT Apps are MCP Apps rendered inside ChatGPT.
What is an MCP App framework?
An MCP App framework provides the development infrastructure for building interactive applications that run inside AI hosts via the Model Context Protocol. Sunpeak is an MCP App framework that includes a local simulator, pre-built UI components, testing utilities, and deployment tooling for building ChatGPT Apps and Claude Apps.
What is a ChatGPT App framework?
A ChatGPT App framework is a development framework for building MCP Apps that run inside ChatGPT. Sunpeak is a ChatGPT App framework that provides a local ChatGPT simulator, MCP App UI components, automated testing with Vitest and Playwright, and deployment tooling.
How do I test an MCP App locally?
Use sunpeak's built-in ChatGPT App simulator. Run "sunpeak dev" to start a local development server at localhost:6767 with hot reloading. The simulator replicates the ChatGPT and MCP App runtime so you can test all display modes, themes, and tool invocations without a paid ChatGPT account.
Does sunpeak support MCP App testing in CI?
Yes. Sunpeak includes Vitest and Playwright integration for automated MCP App testing and ChatGPT App testing. Create deterministic UI states with simulation files, then run "pnpm test" for unit tests or "pnpm test:e2e" for end-to-end tests in your CI/CD pipeline.
