| <!-- LOGO --> |
| <div align="center"> |
| <picture> |
| <source media="(prefers-color-scheme: dark)" srcset="media/mcp-white.svg"> |
| <source media="(prefers-color-scheme: light)" srcset="media/mcp.svg"> |
| <img src="media/mcp.svg" alt="MCP Apps" width="128"> |
| </picture> |
| <h1>MCP Apps</h1> |
| <p> |
| Build interactive UIs for MCP tools — charts, forms, dashboards — that render inline in Claude, ChatGPT and any other compliant chat client. |
| <br /><br /> |
| <a href="#why-mcp-apps">Why</a> |
| · |
| <a href="https://apps.extensions.modelcontextprotocol.io/api/documents/Quickstart.html">Quickstart</a> |
| · |
| <a href="https://apps.extensions.modelcontextprotocol.io/api/">API Docs</a> |
| · |
| <a href="https://github.com/modelcontextprotocol/ext-apps/blob/main/specification/2026-01-26/apps.mdx">Spec</a> |
| · |
| <a href="CONTRIBUTING.md">Contributing</a> |
| </p> |
| </div> |
| |
| <p align="center"> |
| <a href="https://github.com/modelcontextprotocol/ext-apps/actions/workflows/ci.yml"><img src="https://github.com/modelcontextprotocol/ext-apps/actions/workflows/ci.yml/badge.svg" alt="CI"></a> |
| <a href="LICENSE"><img src="https://img.shields.io/badge/license-Apache%202.0-blue" alt="License: Apache 2.0"></a> |
| <a href="https://www.npmjs.com/package/@modelcontextprotocol/ext-apps"><img src="https://img.shields.io/npm/v/@modelcontextprotocol/ext-apps.svg" alt="npm version"></a> |
| <a href="https://www.npmjs.com/package/@modelcontextprotocol/ext-apps"><img src="https://img.shields.io/npm/dm/@modelcontextprotocol/ext-apps.svg" alt="npm downloads"></a> |
| <a href="https://github.com/modelcontextprotocol/ext-apps"><img src="https://img.shields.io/github/stars/modelcontextprotocol/ext-apps" alt="GitHub stars"></a> |
| <a href="https://apps.extensions.modelcontextprotocol.io/api/"><img src="https://img.shields.io/badge/docs-API%20Reference-blue" alt="API Documentation"></a> |
| </p> |
|
|
| <p align="center"> |
| <img src="media/excalidraw.gif" alt="MCP Apps demo" width="600"> |
| <br><em>Excalidraw built with MCP Apps, running in Claude</em> |
| </p> |
|
|
| ## Table of Contents |
|
|
| - [Build with Agent Skills](#build-with-agent-skills) |
| - [Supported Clients](#supported-clients) |
| - [Why MCP Apps?](#why-mcp-apps) |
| - [How It Works](#how-it-works) |
| - [Getting Started](#getting-started) |
| - [Using the SDK](#using-the-sdk) |
| - [Examples](#examples) |
| - [Specification](#specification) |
| - [Resources](#resources) |
| - [Contributing](#contributing) |
|
|
| ## Build with Agent Skills |
|
|
| The fastest way to build an MCP App is to let your AI coding agent do it. This |
| repo ships four [Agent Skills](https://agentskills.io/) — install them once, |
| then just ask: |
|
|
| | Skill | What it does | Try it | |
| | --------------------------------------------------------------------------- | ----------------------------------------------------------- | ------------------------------------- | |
| | [`create-mcp-app`](./plugins/mcp-apps/skills/create-mcp-app/SKILL.md) | Scaffolds a new MCP App with an interactive UI from scratch | _"Create an MCP App"_ | |
| | [`migrate-oai-app`](./plugins/mcp-apps/skills/migrate-oai-app/SKILL.md) | Converts an existing OpenAI App to use MCP Apps | _"Migrate from OpenAI Apps SDK"_ | |
| | [`add-app-to-server`](./plugins/mcp-apps/skills/add-app-to-server/SKILL.md) | Adds interactive UI to an existing MCP server's tools | _"Add UI to my MCP server"_ | |
| | [`convert-web-app`](./plugins/mcp-apps/skills/convert-web-app/SKILL.md) | Turns an existing web app into a hybrid web + MCP App | _"Add MCP App support to my web app"_ | |
|
|
| ### Install the Skills |
|
|
| **Claude Code** — install via the plugin marketplace: |
|
|
| ``` |
| /plugin marketplace add modelcontextprotocol/ext-apps |
| /plugin install mcp-apps@modelcontextprotocol-ext-apps |
| ``` |
|
|
| **Other agents** — any AI coding agent that supports |
| [Agent Skills](https://agentskills.io/) can use these skills. See the |
| [agent skills guide](./docs/agent-skills.md) for manual installation |
| instructions. |
|
|
| Once installed, verify by asking your agent _"What skills do you have?"_ — you |
| should see `create-mcp-app`, `migrate-oai-app`, `add-app-to-server`, and |
| `convert-web-app` in the list. Then just ask it to create or migrate an app and |
| it will guide you through the rest. |
|
|
| ## Supported Clients |
|
|
| <p align="center"> |
| <a href="https://developers.openai.com/apps-sdk/mcp-apps-in-chatgpt/"><img src="https://img.shields.io/badge/ChatGPT-docs-74aa9c?logo=openai&logoColor=white" alt="ChatGPT"></a> |
| <a href="https://claude.com/docs/connectors/building/mcp-apps/getting-started"><img src="https://img.shields.io/badge/Claude-docs-d97706?logo=claude&logoColor=white" alt="Claude"></a> |
| <a href="https://code.visualstudio.com/blogs/2026/01/26/mcp-apps-support"><img src="https://img.shields.io/badge/VS_Code-docs-007ACC?logo=visualstudiocode&logoColor=white" alt="VS Code"></a> |
| <a href="https://block.github.io/goose/docs/tutorials/building-mcp-apps/"><img src="https://img.shields.io/badge/Goose-docs-000000?logo=goose&logoColor=white" alt="Goose"></a> |
| <a href="https://learning.postman.com/docs/postman-ai/mcp-requests/interact"><img src="https://img.shields.io/badge/Postman-docs-FF6C37?logo=postman&logoColor=white" alt="Postman"></a> |
| <a href="https://www.mcpjam.com/blog/mcp-apps-example"><img src="https://img.shields.io/badge/MCPJam-docs-8B5CF6" alt="MCPJam"></a> |
| </p> |
|
|
| > [!NOTE] |
| > MCP Apps is an extension to the |
| > [core MCP specification](https://modelcontextprotocol.io/specification). Host |
| > support varies — see the |
| > [clients page](https://modelcontextprotocol.io/clients) for the full list. |
|
|
| ## Why MCP Apps? |
|
|
| MCP tools return text and structured data. That works for many cases, but not |
| when you need an interactive UI, like a chart, form, design canvas or video player. |
|
|
| MCP Apps provide a standardized way to deliver interactive UIs from MCP servers. |
| Your UI renders inline in the conversation, in context, in any compliant host. |
|
|
| ## How It Works |
|
|
| MCP Apps extend the Model Context Protocol by letting tools declare UI |
| resources: |
|
|
| 1. **Tool definition** — Your tool declares a `ui://` resource containing its |
| HTML interface |
| 2. **Tool call** — The LLM calls the tool on your server |
| 3. **Host renders** — The host fetches the resource and displays it in a |
| sandboxed iframe |
| 4. **Bidirectional communication** — The host passes tool data to the UI via |
| notifications, and the UI can call other tools through the host |
|
|
| ## Getting Started |
|
|
| ```bash |
| npm install -S @modelcontextprotocol/ext-apps |
| ``` |
|
|
| **New here?** Start with the |
| [Quickstart Guide](https://apps.extensions.modelcontextprotocol.io/api/documents/Quickstart.html) |
| to build your first MCP App. |
|
|
| ## Using the SDK |
|
|
| The SDK serves three roles: app developers building interactive Views, host |
| developers embedding those Views, and MCP server authors registering tools with |
| UI metadata. |
|
|
| | Package | Purpose | Docs | |
| | ------------------------------------------- | --------------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------- | |
| | `@modelcontextprotocol/ext-apps` | Build interactive Views (App class, PostMessageTransport) | [API Docs →](https://apps.extensions.modelcontextprotocol.io/api/modules/app.html) | |
| | `@modelcontextprotocol/ext-apps/react` | React hooks for Views (useApp, useHostStyles, etc.) | [API Docs →](https://apps.extensions.modelcontextprotocol.io/api/modules/_modelcontextprotocol_ext-apps_react.html) | |
| | `@modelcontextprotocol/ext-apps/app-bridge` | Embed and communicate with Views in your chat client | [API Docs →](https://apps.extensions.modelcontextprotocol.io/api/modules/app-bridge.html) | |
| | `@modelcontextprotocol/ext-apps/server` | Register tools and resources on your MCP server | [API Docs →](https://apps.extensions.modelcontextprotocol.io/api/modules/server.html) | |
|
|
| There's no _supported_ host implementation in this repo (beyond the |
| [examples/basic-host](https://github.com/modelcontextprotocol/ext-apps/tree/main/examples/basic-host) |
| example). |
|
|
| The [MCP-UI](https://github.com/idosal/mcp-ui) client SDK offers a |
| fully-featured MCP Apps framework used by a few hosts. Clients may choose to use |
| it or roll their own implementation. |
|
|
| ## Examples |
|
|
| The |
| [`examples/`](https://github.com/modelcontextprotocol/ext-apps/tree/main/examples) |
| directory contains demo apps showcasing real-world use cases. |
|
|
| <!-- prettier-ignore-start --> |
| | | | | |
| |:---:|:---:|:---:| |
| | [](https://github.com/modelcontextprotocol/ext-apps/tree/main/examples/map-server) | [](https://github.com/modelcontextprotocol/ext-apps/tree/main/examples/threejs-server) | [](https://github.com/modelcontextprotocol/ext-apps/tree/main/examples/shadertoy-server) | |
| | [**Map**](https://github.com/modelcontextprotocol/ext-apps/tree/main/examples/map-server) | [**Three.js**](https://github.com/modelcontextprotocol/ext-apps/tree/main/examples/threejs-server) | [**ShaderToy**](https://github.com/modelcontextprotocol/ext-apps/tree/main/examples/shadertoy-server) | |
| | [](https://github.com/modelcontextprotocol/ext-apps/tree/main/examples/sheet-music-server) | [](https://github.com/modelcontextprotocol/ext-apps/tree/main/examples/wiki-explorer-server) | [](https://github.com/modelcontextprotocol/ext-apps/tree/main/examples/cohort-heatmap-server) | |
| | [**Sheet Music**](https://github.com/modelcontextprotocol/ext-apps/tree/main/examples/sheet-music-server) | [**Wiki Explorer**](https://github.com/modelcontextprotocol/ext-apps/tree/main/examples/wiki-explorer-server) | [**Cohort Heatmap**](https://github.com/modelcontextprotocol/ext-apps/tree/main/examples/cohort-heatmap-server) | |
| | [](https://github.com/modelcontextprotocol/ext-apps/tree/main/examples/scenario-modeler-server) | [](https://github.com/modelcontextprotocol/ext-apps/tree/main/examples/budget-allocator-server) | [](https://github.com/modelcontextprotocol/ext-apps/tree/main/examples/customer-segmentation-server) | |
| | [**Scenario Modeler**](https://github.com/modelcontextprotocol/ext-apps/tree/main/examples/scenario-modeler-server) | [**Budget Allocator**](https://github.com/modelcontextprotocol/ext-apps/tree/main/examples/budget-allocator-server) | [**Customer Segmentation**](https://github.com/modelcontextprotocol/ext-apps/tree/main/examples/customer-segmentation-server) | |
| | [](https://github.com/modelcontextprotocol/ext-apps/tree/main/examples/system-monitor-server) | [](https://github.com/modelcontextprotocol/ext-apps/tree/main/examples/transcript-server) | [](https://github.com/modelcontextprotocol/ext-apps/tree/main/examples/video-resource-server) | |
| | [**System Monitor**](https://github.com/modelcontextprotocol/ext-apps/tree/main/examples/system-monitor-server) | [**Transcript**](https://github.com/modelcontextprotocol/ext-apps/tree/main/examples/transcript-server) | [**Video Resource**](https://github.com/modelcontextprotocol/ext-apps/tree/main/examples/video-resource-server) | |
| | [](https://github.com/modelcontextprotocol/ext-apps/tree/main/examples/pdf-server) | [](https://github.com/modelcontextprotocol/ext-apps/tree/main/examples/qr-server) | [](https://github.com/modelcontextprotocol/ext-apps/tree/main/examples/say-server) | |
| | [**PDF Server**](https://github.com/modelcontextprotocol/ext-apps/tree/main/examples/pdf-server) | [**QR Code (Python)**](https://github.com/modelcontextprotocol/ext-apps/tree/main/examples/qr-server) | [**Say Demo**](https://github.com/modelcontextprotocol/ext-apps/tree/main/examples/say-server) | |
|
|
| ### Starter Templates |
|
|
| | | | |
| |:---:|:---| |
| | [](https://github.com/modelcontextprotocol/ext-apps/tree/main/examples/basic-server-react) | The same app built with different frameworks — pick your favorite!<br><br>[React](https://github.com/modelcontextprotocol/ext-apps/tree/main/examples/basic-server-react) · [Vue](https://github.com/modelcontextprotocol/ext-apps/tree/main/examples/basic-server-vue) · [Svelte](https://github.com/modelcontextprotocol/ext-apps/tree/main/examples/basic-server-svelte) · [Preact](https://github.com/modelcontextprotocol/ext-apps/tree/main/examples/basic-server-preact) · [Solid](https://github.com/modelcontextprotocol/ext-apps/tree/main/examples/basic-server-solid) · [Vanilla JS](https://github.com/modelcontextprotocol/ext-apps/tree/main/examples/basic-server-vanillajs) | |
| <!-- prettier-ignore-end --> |
|
|
| ### Running the Examples |
|
|
| #### With basic-host |
|
|
| To run all examples locally using |
| [basic-host](https://github.com/modelcontextprotocol/ext-apps/tree/main/examples/basic-host) |
| (the reference host implementation included in this repo): |
|
|
| ```bash |
| git clone https://github.com/modelcontextprotocol/ext-apps.git |
| cd ext-apps |
| npm install |
| npm start |
| ``` |
|
|
| Then open http://localhost:8080/. |
|
|
| #### With MCP Clients |
|
|
| Every Node.js example is published as `@modelcontextprotocol/server-<name>`. To |
| add one to an MCP client that supports stdio (Claude Desktop, VS Code, etc.), |
| use this pattern: |
|
|
| ```json |
| { |
| "mcpServers": { |
| "<name>": { |
| "command": "npx", |
| "args": ["-y", "@modelcontextprotocol/server-<name>", "--stdio"] |
| } |
| } |
| } |
| ``` |
|
|
| For example, to add the map server: `@modelcontextprotocol/server-map`. The |
| Python examples (`qr-server`, `say-server`) use `uv run` instead — see their |
| READMEs for details. |
|
|
| #### Local Development |
|
|
| To test local modifications with an MCP client, clone the repo, install, then |
| point your client at a local build: |
|
|
| ```json |
| { |
| "mcpServers": { |
| "<name>": { |
| "command": "bash", |
| "args": [ |
| "-c", |
| "cd ~/code/ext-apps/examples/<name>-server && npm run build >&2 && node dist/index.js --stdio" |
| ] |
| } |
| } |
| } |
| ``` |
|
|
| ## Specification |
|
|
| <div align="center"> |
|
|
| | Version | Status | Link | |
| | -------------- | ----------- | --------------------------------------------------------------------------------------------------------------------------------- | |
| | **2026-01-26** | Stable | [specification/2026-01-26/apps.mdx](https://github.com/modelcontextprotocol/ext-apps/blob/main/specification/2026-01-26/apps.mdx) | |
| | **draft** | Development | [specification/draft/apps.mdx](https://github.com/modelcontextprotocol/ext-apps/blob/main/specification/draft/apps.mdx) | |
|
|
| </div> |
|
|
| ## Resources |
|
|
| - [Quickstart Guide](https://apps.extensions.modelcontextprotocol.io/api/documents/Quickstart.html) |
| - [API Documentation](https://apps.extensions.modelcontextprotocol.io/api/) |
| - [Specification (2026-01-26)](https://github.com/modelcontextprotocol/ext-apps/blob/main/specification/2026-01-26/apps.mdx) |
| ([Draft](https://github.com/modelcontextprotocol/ext-apps/blob/main/specification/draft/apps.mdx)) |
| - [SEP-1865 Discussion](https://github.com/modelcontextprotocol/modelcontextprotocol/pull/1865) |
|
|
| ## Contributing |
|
|
| Contributions are welcome! Please read [CONTRIBUTING.md](CONTRIBUTING.md) for |
| guidelines on how to get started, submit pull requests, and report issues. |
|
|
