APRS.fi MCP Server

A Model Context Protocol (MCP) server that provides access to APRS.fi API for ham radio position tracking and balloon chase operations. Designed specifically for integration with Claude Code to enable AI-powered APRS data analysis and ham radio operations.

Features

get_aprs_position: Get current position data for a specific callsign
get_aprs_history: Get position history for a callsign with time range
track_multiple_callsigns: Track multiple callsigns at once
validate_aprs_key: Test if an APRS.fi API key is valid
Claude Code Integration: Natural language interface for APRS data analysis

Quick Installation for Claude Code

Easiest Setup (Claude MCP):

npm run build
claude mcp add aprs-fi node dist/index.js

Alternative (Install Script):

./install.sh

For detailed setup instructions, see SETUP.md.

Manual Installation

Install dependencies:

npm install

Build the server:

npm run build

Usage

Starting the Server

npm start

Development Mode

npm run dev

From Main Project

# Build MCP server
npm run mcp:build

# Start MCP server
npm run mcp:start

# Development mode
npm run mcp:dev

MCP Tools

get_aprs_position

Get current position data for a specific callsign from APRS.fi.

Parameters:

callsign (string, required): The callsign to look up (e.g., "W1AW")
apiKey (string, optional): APRS.fi API key (can be set via /set-api-key command)

Returns: Array of APRSPosition objects

get_aprs_history

Get position history for a callsign with time range.

Parameters:

callsign (string, required): The callsign to look up
apiKey (string, optional): APRS.fi API key (can be set via /set-api-key command)
lastHours (number, optional): Number of hours to look back (default: 24)

Returns: Array of APRSPosition objects sorted by timestamp

track_multiple_callsigns

Track multiple callsigns at once.

Parameters:

callsigns (array, required): Array of callsigns to track
apiKey (string, optional): APRS.fi API key (can be set via /set-api-key command)

Returns: Array of APRSPosition objects

validate_aprs_key

Test if an APRS.fi API key is valid.

Parameters:

apiKey (string, optional): APRS.fi API key (can be set via /set-api-key command) to validate

Returns: Object with valid boolean property

Data Types

APRSPosition

interface APRSPosition {
  name: string;           // Callsign
  callsign: string;       // Callsign
  lat: number;           // Latitude in decimal degrees
  lng: number;           // Longitude in decimal degrees
  altitude?: number;     // Altitude in meters (optional)
  timestamp: number;     // Unix timestamp in milliseconds
  comment?: string;      // APRS comment (optional)
  speed?: number;        // Speed in km/h (optional)
  course?: number;       // Course in degrees (optional)
  symbol?: string;       // APRS symbol (optional)
  path?: string;         // APRS path (optional)
}

API Key Setup

Get an API key from APRS.fi
Set it once per session using the /set-api-key command in Claude Code
Alternatively, pass the API key as a parameter to each tool call

Rate Limiting

The server respects APRS.fi rate limits with a 1-second delay between requests.

Error Handling

The server provides detailed error messages for:

Invalid API keys
Network connectivity issues
API rate limiting
Invalid callsigns
API response errors

Claude Code Integration

This MCP server enables Claude Code to access real-time APRS data, making it perfect for:

Ham Radio Operations: Track stations, analyze propagation, coordinate activities
Emergency Communications: Monitor emergency nets and station positions
Balloon Chasing: Track high-altitude balloons and coordinate recovery teams
Contest Support: Monitor contest stations and optimize operations
Educational Projects: Learn about RF propagation and amateur radio

Setup for Claude Code

Easiest Setup (Claude MCP):

# Build the server first
npm run build

# Add to Claude Code
claude mcp add aprs-fi node dist/index.js

Alternative Setup (Install Script):

./install.sh

Manual Configuration: Add this to your ~/.claude/mcp_settings.json:

{
  "mcpServers": {
    "aprs-fi": {
      "command": "node",
      "args": ["/path/to/aprs_mcp/dist/index.js"],
      "env": {}
    }
  }
}

Using with Claude Code

Once installed, Claude Code can help you with APRS data in natural language:

"Show me the current position of W1AW"
"Track these contest stations: N1MM, W5ZZZ, K3LR"
"Get the position history for the balloon callsign KC1SFR-11"
"Find all stations that have been active in the last 2 hours"
"Plot the path of station VE3XYZ over the last 6 hours"

Claude Code will use the MCP tools to fetch real-time data and provide analysis, mapping suggestions, and operational insights.

Slash Commands

/set-api-key <your-key> - Set APRS.fi API key for the session

Development

The server is built using:

@modelcontextprotocol/sdk
TypeScript
Node.js fetch API

License

MIT