Open MCP Apps

What the open-mcp-apps MCP server does

The open-mcp-apps MCP server provides an app registry, a runtime for serving MCP Apps, and persistent storage for app data. An AI agent can read the authoring guidance, create a single-file HTML interface, and save it to the registry. Once registered, the app can be opened by name in later conversations rather than rebuilt each time.

The project separates an app's interface from its data. Apps work with generic collections of items stored in SQLite. Changes are also recorded in an append-only change_event ledger, so the AI and the person using the app operate on the same underlying store.

The repository reports 33 tools and seeds three system apps: settings, dashboard, and App Store. It is distributed under the scoped npm package @2nd1st/open-mcp-apps; the unscoped npm package with a similar name is unrelated.

How it works

The open-mcp-apps MCP server runs locally as a stdio MCP process and binds to 127.0.0.1. When it serves an app through a ui:// resource, it adds the official MCP App bridge, host theme support, and the window.oma API used by the HTML app to access data.

Data mutations use idempotent domain commands identified by command_id. Updates can include expected_version for optimistic concurrency control. This keeps the persistent store independent from the rendered widget: the UI is a view over data that the AI and human can both edit.

The local process can serve hosts on the same machine, including Claude Desktop, Claude Code, and Codex. A browser viewer is also included. Terminal-oriented hosts can drive the same data while the UI appears in a browser screen beside the terminal.

Setup and configuration

Node.js 22 or newer is required on macOS, Windows, and Linux. The simplest setup adds the published package to an MCP host configuration with npx -y @2nd1st/open-mcp-apps. The installer instead clones the repository, installs it into detected hosts, and can register Claude Desktop, Claude Code, or Codex. The installer path requires Git; the npm path does not.

The installer uses ~/open-mcp-apps by default and accepts OMA_DIR to choose another checkout location. Host configuration can also define OMA_VIEWER and PORT; the README shows OMA_VIEWER set to 1 and PORT set to 8787. After installation or updates, fully quit and reopen the host so it starts the new server process.

Uninstalling unregisters the server but preserves the shared data store. The --purge option removes the apps and data, while --check reports registration changes without applying them.

Limitations and notes

The repository's engine is designed for local loopback use. Browser hosts such as claude.ai and ChatGPT web cannot reach that local process, so the documented route for those hosts is the hosted openmcp.app service. Self-hosting the remote deployment is not supported yet.

A host must render ui:// resources to show widgets in the conversation. The engine's stored apps and data live in a fixed per-user store rather than inside the installer checkout, allowing different host registrations to share them. The project is licensed under MIT.