API CALLER MCP SERVER

Universal API caller MCP server supporting all HTTP methods, WebSocket connections, and multiple content types. A complete API testing tool similar to Postman, built as an MCP package.

FEATURES

• All HTTP methods: GET, POST, PUT, PATCH, DELETE, HEAD, OPTIONS
• HTTP and HTTPS protocols
• WebSocket support (ws:// and wss://)
• Multiple body types: JSON, form-data, urlencoded, raw, binary
• File uploads with multipart/form-data
• Image uploads with custom filenames and content types
• Custom headers for all requests
• Query parameters support
• Request timeout control
• Comprehensive error handling
• WebSocket message history and connection management
• Multiple simultaneous WebSocket connections

INSTALLATION

After publishing to npm:

npm install -g @your-scope/package-name

Or use directly with npx (recommended for MCP):

npx -y @your-scope/package-name

CONFIGURATION

Add to your MCP settings:

{ "mcpServers": { "api-caller": { "command": "npx", "args": ["-y", "@your-scope/package-name"] } } }

AVAILABLE TOOLS

HTTP Tools:

• http_request: Full control HTTP request (any method)
• http_get: GET request
• http_post: POST request (any body type)
• http_post_json: POST with JSON body
• http_post_form: POST with multipart/form-data (file uploads)
• http_post_urlencoded: POST with x-www-form-urlencoded
• http_put: PUT request
• http_patch: PATCH request
• http_delete: DELETE request

WebSocket Tools:

• websocket_connect: Connect to WebSocket
• websocket_send: Send message through connection
• websocket_receive: Get received messages
• websocket_close: Close connection
• websocket_info: Get connection details
• websocket_list: List all active connections

BODY TYPES

• json: application/json
• form / multipart: multipart/form-data (for file uploads)
• urlencoded: application/x-www-form-urlencoded
• raw / text: text/plain
• binary: application/octet-stream

USAGE EXAMPLES

Simple GET request: { "url": "https://api.github.com/users/github" }

GET with headers and query params: { "url": "https://api.example.com/search", "headers": { "Authorization": "Bearer YOUR_TOKEN", "Accept": "application/json" }, "queryParams": { "q": "nodejs", "limit": 10 } }

POST JSON data: { "url": "https://api.example.com/users", "body": { "name": "John Doe", "email": "[email protected]" }, "headers": { "Authorization": "Bearer YOUR_TOKEN" } }

POST form-urlencoded: { "url": "https://api.example.com/login", "data": { "username": "user", "password": "pass" } }

Upload file with multipart form: { "url": "https://api.example.com/upload", "fields": { "title": "My Image", "description": "An example image", "image": { "file": "/absolute/path/to/image.jpg", "filename": "photo.jpg", "contentType": "image/jpeg" } } }

POST binary data: { "url": "https://api.example.com/binary", "body": "/path/to/file.bin", "bodyType": "binary" }

WebSocket connection: { "url": "wss://echo.websocket.org", "connectionId": "my-connection", "headers": { "Authorization": "Bearer YOUR_TOKEN" } }

Send WebSocket message: { "connectionId": "my-connection", "message": "Hello WebSocket!" }

Get WebSocket messages: { "connectionId": "my-connection", "limit": 10, "offset": 0 }

ERROR HANDLING

All errors return structured JSON responses:

{ "success": false, "error": { "message": "Error description", "statusCode": 404, "details": {}, "timestamp": "2024-01-30T12:00:00.000Z" } }

SUCCESSFUL RESPONSE

{ "success": true, "request": { "method": "POST", "url": "https://api.example.com/endpoint", "headers": {...}, "bodyType": "json" }, "response": { "status": 200, "statusText": "OK", "headers": {...}, "body": {...} }, "metadata": { "duration": "145ms", "timestamp": "2024-01-30T12:00:00.000Z" } }

REQUIREMENTS

• Node.js >= 18.0.0

PUBLISHING

1. Update package.json with your package name
2. npm login
3. npm publish --access public

LICENSE

MIT License - See LICENSE file for details