sunpeak

Sunpeak is an open-source framework designed for building, testing, and deploying MCP (Model Context Protocol) Apps and connectors that run inside AI hosts such as ChatGPT and Claude. It addresses the complexities of developing interactive UIs for these hosts by providing a convention-over-configuration approach, reducing the need for developers to manage protocol message routing, resource bundling, server setup, and platform-specific code from scratch.

The platform includes a full-stack MCP App framework, a testing framework, and an inspector tool that replicates the ChatGPT and Claude runtimes locally. This enables developers to build, test, and ship MCP Apps and connectors from a single codebase without requiring paid host accounts or AI credits. Sunpeak's inspector allows users to view and interact with their apps as they would appear in production within ChatGPT or Claude, supporting toggling between hosts, themes, display modes, and device types. Hot reloading is available for ChatGPT, and automatic rebuild notifications are provided for Claude, streamlining the development workflow.

Sunpeak offers a suite of features tailored for cross-platform MCP App development, including over 20 typed React hooks for the MCP App runtime, pre-built UI components that adhere to ChatGPT and Claude design guidelines, and a development server with mock data support. The testing framework integrates with Playwright for end-to-end tests, supports live tests against real ChatGPT, visual regression testing across hosts and themes, and can be run in CI/CD pipelines such as GitHub Actions without incurring costs for accounts or API credits. The framework also supports convention-based auto-discovery of tools, resources, and simulations from the file system to further simplify project organization.

Sunpeak is distributed as an npm package, is server-agnostic, and can work with MCP servers written in any language, including Python, Go, TypeScript, Rust, and Java. It is released under the MIT license, making it freely available for open-source use. The tool is aimed at developers creating MCP Apps, ChatGPT Apps, and Claude Connectors who need to streamline their workflow and ensure consistent cross-host compatibility.