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CodingDocumented overviewLast checked Oct 1, 2026

sunpeak: Pricing, Features & Best Use Cases

Open-source (MIT) framework and testing tool for building MCP Apps, ChatGPT Apps and Claude Connectors.

sunpeak homepage screenshot, coding AI tool

Our take: sunpeak suits developers building MCP Apps, ChatGPT Apps or Claude Connectors in React and TypeScript who want one codebase, a local host inspector and Playwright tests, all under an MIT license.

Main limitation: It is a developer framework that needs React, TypeScript and Node tooling, not an end-user AI app.

By the AI Tool Atlas editors. Based on the vendor's official documentation; we have not tested this product hands-on. What “documented overview” means

Who sunpeak fits

sunpeak suits developers building MCP Apps, ChatGPT Apps or Claude Connectors in React and TypeScript who want one codebase, a local host inspector and Playwright tests, all under an MIT license. Based on the vendor's documentation, not on a hands-on test.

Best for: MCP app developers

Also a good fit for

  • Teams building ChatGPT Apps

Consider another tool if developer tool requiring React/TypeScript and Node tooling

Or if

  • No product pricing page found
  • Not a standalone end-user AI app

sunpeak pricing and usage limits

Prices checked Oct 1, 2026 on the official US pricing page. Prices and limits change often.

Free access and trial conditions

Open-source (MIT) npm package; the pricing page returned 404.

Not applicable.

Paid plans: what changes as you upgrade

Open source (MIT) web

Free source (opens in a new tab)

For: Developers building MCP Apps

Limits

  • No pricing page found (HTTP 404)
  • Requires Node and npm

Includes

  • Framework, inspector and dev server
  • Testing framework (sunpeak test)
1 more
  • CLI scaffold and UI components

No API

Usage caps, credits and extra costs

Hosting for your MCP server and any ChatGPT or Claude accounts you choose to use are separate; the site says CI testing needs no paid accounts or API credits.

Not applicable.

What is sunpeak, and how does it work?

sunpeak is a server-agnostic MCP testing framework and full-stack MCP App framework. MCP Apps are interactive UIs that run inside AI hosts such as ChatGPT and Claude. It offers a CLI scaffold (npx sunpeak new), a hot-reloading dev server with mock data, an inspector replicating ChatGPT and Claude runtimes, React hooks and UI components, and Playwright-based tests.

sunpeak homepage — screenshot of the coding AI tool, Oct 2, 2026
sunpeak's official site: how the product presents itself. sunpeak.ai, captured Oct 2, 2026

What you provide and what you get back

How sunpeak works: what you provide, where it runs and what you get backYOU PROVIDEYour inputTypeScript tool handlers and Reac…Simulation JSON mock dataAn existing MCP server URL for te…CODINGsunpeakAPIfree tier, paid price not publish…free tier availablechecked Oct 1, 2026YOU GET BACKThe resultAn MCP App that runs in ChatGPT a…Inspector renders of tools in rep…Playwright test resultsinput → sunpeak → output · from the vendor's own pages, no hands-on test unless stated
What you give sunpeak and what comes back, from its documentation

You provide

  • TypeScript tool handlers and React resource components
  • Simulation JSON mock data
  • An existing MCP server URL for testing

You get back

  • An MCP App that runs in ChatGPT and Claude
  • Inspector renders of tools in replicated hosts
  • Playwright test results

Where you can use it

Platforms
API
Account
Not required
Languages
TypeScript and React
Install
npm package sunpeak; npx sunpeak new
Test tooling
Playwright E2E, visual regression, multi-model evals
Hosts
ChatGPT and Claude runtimes in the inspector
License
MIT

Where sunpeak is most useful

Scenarios are worked out by our editors from the documentation; the actual result depends on your input and plan.

Build ChatGPT Apps

Who
Developers shipping ChatGPT Apps
You provide
A React UI component and a tool handler
Expected result
An app that renders inside ChatGPT via MCP
Plan needed
Open source
Limitation
ChatGPT apps are published as plugins per the docs source (opens in a new tab)

Build Claude Connectors

Who
Teams building Claude Connectors
You provide
The same tool and resource code
Expected result
A connector rendered inside Claude from one codebase
Plan needed
Open source
Limitation
Host capabilities differ and need testing source (opens in a new tab)

Test MCP servers end to end

Who
QA engineers for MCP servers
You provide
An MCP server URL in any language
Expected result
End-to-end tests and visual regression across hosts and themes
Plan needed
Open source
Limitation
Live host tests need a real ChatGPT account source (opens in a new tab)

sunpeak features and their limits

sunpeak homepage — screenshot of the coding AI tool, Oct 2, 2026
Feature overview on the official site. sunpeak.ai, captured Oct 2, 2026

MCP App framework

Provides a convention-over-configuration framework where tools, resources and simulations are auto-discovered from the file system. Removes MCP server and bundle wiring.

Access: Open sourceLimit: Opinionated structure to learn. source (opens in a new tab)

Playwright E2E testing framework

Runs Playwright end-to-end tests against the inspector, with visual regression and CI support. Tests MCP Apps without deploying to hosts.

Access: sunpeak testLimit: Standard browser tests cannot replicate host iframes without it. source (opens in a new tab)

MCP App Inspector with ChatGPT and Claude runtimes

Offers an inspector that replicates ChatGPT and Claude runtimes with light/dark themes and display modes. Lets you see the app in both hosts locally.

Access: npx sunpeak inspectLimit: Replicates runtimes; it is not the real hosts. source (opens in a new tab)

Hot-reloading MCP dev server with mock data

Runs a hot-reloading MCP dev server with mock data. Speeds iteration on the UI.

Access: Dev serverLimit: Mock data must be written as simulations. source (opens in a new tab)

sunpeak: strengths and limits

Reasons to choose sunpeak

Check before paying for sunpeak

How to use sunpeak for scaffolding and testing an MCP App

sunpeak documentation — screenshot of the coding AI tool, Oct 2, 2026
sunpeak documentation: where the steps below come from. sunpeak.ai, captured Oct 2, 2026

Set up sunpeak

  1. Install Node and run npx sunpeak new to scaffold an app
  2. Install dependencies and start the dev server
  3. Optionally add the coding-agent skills from the docs

Example: scaffolding and testing an MCP App

  1. Write a tool handler in src/tools with its schema
  2. Create the React component in src/resources
  3. Add mock data in tests/simulations and open the inspector
  4. Switch between ChatGPT and Claude hosts and themes in the inspector

Review and export the result

  1. Run npx sunpeak test and confirm the Playwright tests pass
  2. Check screenshots across hosts and themes for regressions

sunpeak API

sunpeak documentation — screenshot of the coding AI tool, Oct 2, 2026
sunpeak documentation (continued). sunpeak.ai, captured Oct 2, 2026

API access and separate billing

sunpeak has no public API in its official documentation. npm package with CLI and React hooks; docs also available via MCP at sunpeak.ai/docs/mcp. API documentation ↗

Other tools to consider instead of sunpeak

"Better suited" is based on documented features and pricing, not on a head-to-head test.

Cursor: better suited to

GitHub Copilot: better suited to

Alternatives
AlternativeWhen to choose itPricingLimitation
Cursor——Compare
GitHub Copilot——Compare

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    sunpeak FAQ

    What license does sunpeak use?

    MIT, so it is open source and free for commercial use. source (opens in a new tab)

    How do I start a sunpeak project?

    Run npx sunpeak new to scaffold an MCP App, then use the dev server and inspector. source (opens in a new tab)

    Can sunpeak test an MCP server written in Python or Go?

    Yes. The inspector works with any MCP server in any language, using npx sunpeak inspect --server . source (opens in a new tab)

    Does sunpeak testing need paid accounts?

    CI tests against the inspector need no paid accounts or API credits; live host tests run against real ChatGPT. source (opens in a new tab)

    What is an MCP App?

    An interactive UI embedded in an agent conversation via the Model Context Protocol, such as a ChatGPT App or Claude Connector. source (opens in a new tab)

    Sources and review methodology

    Official sources and verification dates

    Not verified: Pricing beyond open source; Privacy policy; Support options.

    How we documented and maintain this page

    Every fact about sunpeak above comes from the 3 official pages listed here, last compared on Oct 1, 2026; we have not run sunpeak ourselves, so it has no editorial score. How we check and re-check pages.

    Article updated Oct 2, 2026; prices checked Oct 1, 2026. Outbound links to vendors are plain links; we do not earn commissions. How we review · Report an error