sunpeak
Build, test, and inspect MCP Apps for ChatGPT and Claude with sunpeak. Open-source framework with hot reload, Playwright tests, and host simulation.
Editor's Verdict
Key Takeaways
- MCP App Framework
- Testing Framework
- MCP App Inspector
- MCP Dev Server
In-Depth Review: What is sunpeak?
sunpeak is a powerful, open-source MCP App framework and testing platform that lets you build, test, and deploy interactive UIs for ChatGPT and Claude—all from a single codebase. With built-in tools like a hot-reloading dev server, a local inspector that simulates host environments, and Playwright-based testing, you can rapidly develop cross-platform MCP Apps without needing paid AI accounts or credits. Whether you're creating ChatGPT Apps or Claude Connectors, sunpeak streamlines the entire workflow with convention-over-configuration, pre-built UI components, and robust CI/CD support.
Core Features
MCP App Framework
Full-stack framework for building interactive UIs that run inside AI hosts like ChatGPT and Claude via the Model Context Protocol.
Testing Framework
Playwright E2E tests and live tests against real ChatGPT, with simulation fixtures for CI/CD testing without accounts or API credits.
MCP App Inspector
Replicates ChatGPT and Claude runtimes locally to inspect and debug MCP Apps across different hosts, themes, and devices.
MCP Dev Server
Hot-reloading MCP server with mock data, with HMR in ChatGPT and automatic rebuild notifications in Claude.
MCP App UI Components
Pre-built UI components following ChatGPT and Claude design guidelines for cross-platform MCP App development.
MCP App APIs
20+ typed React hooks (e.g., useToolData, useAppState, useTheme) for building MCP Apps.
CLI Tools
Scaffold, build, test, and ship MCP Apps with a simple CLI (e.g., npx sunpeak new).
Convention-over-configuration
Auto-discovery of tools, resources, and simulations from the file system, reducing boilerplate.
Pricing
Open Source (MIT)
- All framework features
- Testing framework
- Inspector
- Dev server
- UI components
- APIs
- CLI tools
- No paid accounts or AI credits needed for development and testing
Pros and Cons
Pros
- Open Source & MIT LicensedFree to use, modify, and distribute with no licensing costs or vendor lock-in.
- Cross-Platform CompatibilityWrite once and deploy across ChatGPT, Claude, and future MCP-compatible hosts.
- Built-in Testing & InspectionIntegrated Playwright E2E testing and a local inspector that replicates host runtimes, enabling comprehensive CI/CD testing.
- Hot ReloadingInstant updates via HMR in ChatGPT and automatic rebuild notifications in Claude, streamlining development.
- Convention-over-ConfigurationAuto-discovery of tools and resources from the file system reduces boilerplate and accelerates development.
Cons
- Dependency on MCP EcosystemRelies on the Model Context Protocol; limited to hosts that support MCP (ChatGPT, Claude, etc.).
- Relatively New FrameworkAs a newer project, community size and third-party resources may be limited compared to established frameworks.
- Learning Curve for MCP ConceptsDevelopers need to understand the MCP protocol and sunpeak's conventions, which may require initial effort.
Use Cases & Recommended Professions
AI App Developer→ View Toolkit
Builds interactive UIs for AI hosts; needs a framework to create ChatGPT Apps and Claude Connectors efficiently.
MCP Server Developer→ View Toolkit
Develops MCP servers; uses sunpeak to test and inspect their servers' tools and resources in simulated host environments.
QA Engineer→ View Toolkit
Tests MCP Apps across multiple hosts and themes; leverages sunpeak's testing framework for automated E2E and visual regression tests.
Full-Stack Developer→ View Toolkit
Integrates AI assistants into web applications; benefits from sunpeak's full-stack capabilities and convention-over-configuration.
DevOps Engineer→ View Toolkit
Sets up CI/CD pipelines for MCP App deployment; uses sunpeak's testing framework that runs in GitHub Actions without accounts or credits.
Product Manager (AI Features)→ View Toolkit
Oversees AI feature development; uses sunpeak to rapidly prototype and test ChatGPT/Claude integrations without paid accounts.
Frequently Asked Questions
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ℹ️ Curation Disclosure: The overview and features of sunpeak were synthesized using AI and fact-checked by our curation team to ensure accuracy.
