Add MCP App Support to a Web App

Add MCP App support to an existing web application so it works both as a standalone web app and as an MCP App that renders inline in MCP-enabled hosts like Claude Desktop — from a single codebase.

How It Works

The existing web app stays intact. A thin initialization layer detects whether the app is running inside an MCP host or as a regular web page, and fetches parameters from the appropriate source. A new MCP server wraps the app's bundled HTML as a resource and registers a tool to display it.

Standalone:  Browser loads page → App reads URL params / APIs → renders
MCP App:     Host calls tool → Server returns result → Host renders app in iframe → App reads MCP lifecycle → renders

The app's rendering logic is shared — only the data source changes.

Getting Reference Code

Clone the SDK repository for working examples and API documentation: