a870456893* fix(readme): use picture element for theme-aware logo The #gh-light-mode-only / #gh-dark-mode-only URL fragments only work on github.com. On npm, VS Code preview, and other markdown renderers both img tags render, showing two stacked logos. Switch to <picture> with prefers-color-scheme, which GitHub recommends and which degrades gracefully to a single logo elsewhere. * ci: add Cloudflare Pages preview for docs PRs Deploys a per-PR preview of the TypeDoc site to Cloudflare Pages project mcp-ext-apps-docs-preview when docs, src JSDoc, README, or typedoc config change. Uses the shared modelcontextprotocol/actions composite action that injects noindex headers, posts a sticky PR comment with preview URLs, and cleans up deployments on PR close. Fork PRs are skipped (no secret access). * fix(docs): sync README logo with TypeDoc theme switcher The README <picture> logo uses prefers-color-scheme, which only follows the OS setting. TypeDoc's theme switcher sets data-theme on <html>, so manually picking Light/Dark would show the wrong logo (e.g. white logo on light background if OS is dark but user picked Light). Rewrite the <picture> in the generated docs into two class-tagged <img>s via the mcpstyle plugin, and hide the inactive one via CSS keyed on both data-theme (explicit selection) and prefers-color-scheme (OS mode). The README source is unchanged so GitHub/npm still get <picture>. Also: prettier normalized mcp-theme.css (tabs to spaces, quote style).
258 lines
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Markdown
258 lines
17 KiB
Markdown
<!-- LOGO -->
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<div align="center">
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<picture>
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<source media="(prefers-color-scheme: dark)" srcset="media/mcp-white.svg">
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<source media="(prefers-color-scheme: light)" srcset="media/mcp.svg">
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<img src="media/mcp.svg" alt="MCP Apps" width="128">
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</picture>
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<h1>MCP Apps</h1>
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<p>
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Build interactive UIs for MCP tools — charts, forms, dashboards — that render inline in Claude, ChatGPT and any other compliant chat client.
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<br /><br />
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<a href="#why-mcp-apps">Why</a>
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·
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<a href="https://apps.extensions.modelcontextprotocol.io/api/documents/Quickstart.html">Quickstart</a>
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·
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<a href="https://apps.extensions.modelcontextprotocol.io/api/">API Docs</a>
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·
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<a href="https://github.com/modelcontextprotocol/ext-apps/blob/main/specification/2026-01-26/apps.mdx">Spec</a>
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·
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<a href="CONTRIBUTING.md">Contributing</a>
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</p>
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</div>
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<p align="center">
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<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>
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<a href="LICENSE"><img src="https://img.shields.io/badge/license-Apache%202.0-blue" alt="License: Apache 2.0"></a>
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<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>
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<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>
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<a href="https://github.com/modelcontextprotocol/ext-apps"><img src="https://img.shields.io/github/stars/modelcontextprotocol/ext-apps" alt="GitHub stars"></a>
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<a href="https://apps.extensions.modelcontextprotocol.io/api/"><img src="https://img.shields.io/badge/docs-API%20Reference-blue" alt="API Documentation"></a>
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</p>
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<p align="center">
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<img src="media/excalidraw.gif" alt="MCP Apps demo" width="600">
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<br><em>Excalidraw built with MCP Apps, running in Claude</em>
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</p>
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## Table of Contents
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- [Build with Agent Skills](#build-with-agent-skills)
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- [Supported Clients](#supported-clients)
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- [Why MCP Apps?](#why-mcp-apps)
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- [How It Works](#how-it-works)
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- [Getting Started](#getting-started)
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- [Using the SDK](#using-the-sdk)
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- [Examples](#examples)
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- [Specification](#specification)
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- [Resources](#resources)
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- [Contributing](#contributing)
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## Build with Agent Skills
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The fastest way to build an MCP App is to let your AI coding agent do it. This
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repo ships four [Agent Skills](https://agentskills.io/) — install them once,
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then just ask:
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| Skill | What it does | Try it |
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| --------------------------------------------------------------------------- | ----------------------------------------------------------- | ------------------------------------- |
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| [`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"_ |
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| [`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"_ |
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| [`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"_ |
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| [`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"_ |
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### Install the Skills
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**Claude Code** — install via the plugin marketplace:
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```
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/plugin marketplace add modelcontextprotocol/ext-apps
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/plugin install mcp-apps@modelcontextprotocol-ext-apps
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```
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**Other agents** — any AI coding agent that supports
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[Agent Skills](https://agentskills.io/) can use these skills. See the
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[agent skills guide](./docs/agent-skills.md) for manual installation
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instructions.
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Once installed, verify by asking your agent _"What skills do you have?"_ — you
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should see `create-mcp-app`, `migrate-oai-app`, `add-app-to-server`, and
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`convert-web-app` in the list. Then just ask it to create or migrate an app and
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it will guide you through the rest.
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## Supported Clients
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<p align="center">
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<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>
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<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>
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<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>
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<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>
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<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>
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<a href="https://www.mcpjam.com/blog/mcp-apps-example"><img src="https://img.shields.io/badge/MCPJam-docs-8B5CF6" alt="MCPJam"></a>
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</p>
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> [!NOTE]
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> MCP Apps is an extension to the
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> [core MCP specification](https://modelcontextprotocol.io/specification). Host
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> support varies — see the
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> [clients page](https://modelcontextprotocol.io/clients) for the full list.
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## Why MCP Apps?
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MCP tools return text and structured data. That works for many cases, but not
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when you need an interactive UI, like a chart, form, design canvas or video player.
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MCP Apps provide a standardized way to deliver interactive UIs from MCP servers.
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Your UI renders inline in the conversation, in context, in any compliant host.
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## How It Works
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MCP Apps extend the Model Context Protocol by letting tools declare UI
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resources:
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1. **Tool definition** — Your tool declares a `ui://` resource containing its
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HTML interface
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2. **Tool call** — The LLM calls the tool on your server
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3. **Host renders** — The host fetches the resource and displays it in a
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sandboxed iframe
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4. **Bidirectional communication** — The host passes tool data to the UI via
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notifications, and the UI can call other tools through the host
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## Getting Started
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```bash
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npm install -S @modelcontextprotocol/ext-apps
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```
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**New here?** Start with the
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[Quickstart Guide](https://apps.extensions.modelcontextprotocol.io/api/documents/Quickstart.html)
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to build your first MCP App.
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## Using the SDK
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The SDK serves three roles: app developers building interactive Views, host
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developers embedding those Views, and MCP server authors registering tools with
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UI metadata.
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| Package | Purpose | Docs |
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| ------------------------------------------- | --------------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------- |
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| `@modelcontextprotocol/ext-apps` | Build interactive Views (App class, PostMessageTransport) | [API Docs →](https://apps.extensions.modelcontextprotocol.io/api/modules/app.html) |
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| `@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) |
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| `@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) |
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| `@modelcontextprotocol/ext-apps/server` | Register tools and resources on your MCP server | [API Docs →](https://apps.extensions.modelcontextprotocol.io/api/modules/server.html) |
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There's no _supported_ host implementation in this repo (beyond the
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[examples/basic-host](https://github.com/modelcontextprotocol/ext-apps/tree/main/examples/basic-host)
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example).
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The [MCP-UI](https://github.com/idosal/mcp-ui) client SDK offers a
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fully-featured MCP Apps framework used by a few hosts. Clients may choose to use
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it or roll their own implementation.
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## Examples
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The
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[`examples/`](https://github.com/modelcontextprotocol/ext-apps/tree/main/examples)
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directory contains demo apps showcasing real-world use cases.
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<!-- prettier-ignore-start -->
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| | | |
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|:---:|:---:|:---:|
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| [](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) |
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| [**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) |
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| [](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) |
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| [**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) |
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| [](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) |
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| [**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) |
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| [](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) |
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| [**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) |
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| [](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) |
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| [**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) |
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### Starter Templates
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|:---:|:---|
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| [](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) |
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<!-- prettier-ignore-end -->
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### Running the Examples
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#### With basic-host
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To run all examples locally using
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[basic-host](https://github.com/modelcontextprotocol/ext-apps/tree/main/examples/basic-host)
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(the reference host implementation included in this repo):
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```bash
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git clone https://github.com/modelcontextprotocol/ext-apps.git
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cd ext-apps
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npm install
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npm start
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```
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Then open http://localhost:8080/.
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#### With MCP Clients
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Every Node.js example is published as `@modelcontextprotocol/server-<name>`. To
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add one to an MCP client that supports stdio (Claude Desktop, VS Code, etc.),
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use this pattern:
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```json
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{
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"mcpServers": {
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"<name>": {
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"command": "npx",
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"args": ["-y", "@modelcontextprotocol/server-<name>", "--stdio"]
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}
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}
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}
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```
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For example, to add the map server: `@modelcontextprotocol/server-map`. The
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Python examples (`qr-server`, `say-server`) use `uv run` instead — see their
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READMEs for details.
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#### Local Development
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To test local modifications with an MCP client, clone the repo, install, then
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point your client at a local build:
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```json
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{
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"mcpServers": {
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"<name>": {
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"command": "bash",
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"args": [
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"-c",
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"cd ~/code/ext-apps/examples/<name>-server && npm run build >&2 && node dist/index.js --stdio"
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]
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}
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}
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}
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```
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## Specification
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<div align="center">
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| Version | Status | Link |
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| -------------- | ----------- | --------------------------------------------------------------------------------------------------------------------------------- |
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| **2026-01-26** | Stable | [specification/2026-01-26/apps.mdx](https://github.com/modelcontextprotocol/ext-apps/blob/main/specification/2026-01-26/apps.mdx) |
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| **draft** | Development | [specification/draft/apps.mdx](https://github.com/modelcontextprotocol/ext-apps/blob/main/specification/draft/apps.mdx) |
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</div>
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## Resources
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- [Quickstart Guide](https://apps.extensions.modelcontextprotocol.io/api/documents/Quickstart.html)
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- [API Documentation](https://apps.extensions.modelcontextprotocol.io/api/)
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- [Specification (2026-01-26)](https://github.com/modelcontextprotocol/ext-apps/blob/main/specification/2026-01-26/apps.mdx)
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([Draft](https://github.com/modelcontextprotocol/ext-apps/blob/main/specification/draft/apps.mdx))
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- [SEP-1865 Discussion](https://github.com/modelcontextprotocol/modelcontextprotocol/pull/1865)
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## Contributing
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Contributions are welcome! Please read [CONTRIBUTING.md](CONTRIBUTING.md) for
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guidelines on how to get started, submit pull requests, and report issues.
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