A demo MCP App that displays cohort retention data as an interactive heatmap, showing customer retention over time by signup month.

Add to your MCP client configuration (stdio transport):

{
  "mcpServers": {
    "cohort-heatmap": {
      "command": "npx",
      "args": [
        "-y",
        "--silent",
        "--registry=https://registry.npmjs.org/",
        "@modelcontextprotocol/server-cohort-heatmap",
        "--stdio"
      ]
    }
  }
}

To test local modifications, use this configuration (replace ~/code/ext-apps with your clone path):

{
  "mcpServers": {
    "cohort-heatmap": {
      "command": "bash",
      "args": [
        "-c",
        "cd ~/code/ext-apps/examples/cohort-heatmap-server && npm run build >&2 && node dist/index.js --stdio"
      ]
    }
  }
}

• Cohort Retention Heatmap: Color-coded grid showing retention percentages across cohorts and time periods
• Multiple Metrics: Switch between Retention %, Revenue Retention, and Active Users
• Period Types: View data by monthly or weekly intervals
• Interactive Exploration: Hover cells for detailed tooltips, click to highlight rows/columns
• Color Scale: Green (high retention) through yellow to red (low retention)
• Theme Support: Adapts to light/dark mode preferences

1. Install dependencies:

   npm install

2. Build and start the server:

   npm run start:http  # for Streamable HTTP transport
   # OR
   npm run start:stdio  # for stdio transport

3. View using the basic-host example or another MCP Apps-compatible host.

Exposes a single get-cohort-data tool that returns:

• Cohort rows with signup month, original user count, and retention cells
• Period headers and labels
• Configurable parameters: metric type, period type, cohort count, max periods

The tool generates synthetic cohort data using an exponential decay model with configurable retention curves per metric type.

• Uses React for the heatmap visualization
• Fetches data on mount and when filters change
• Displays retention percentages in a grid with HSL color interpolation
• Shows detailed tooltips on hover with user counts and exact retention values
• Supports row/column highlighting on cell click