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WebSocket Clients: Postman & Other Tools

Testing and interacting with WebSocket APIs is easier with dedicated tools. This page covers how to use Postman, browser extensions, and standalone apps to connect, send, and debug WebSocket traffic.

🛠 1. Postman WebSocket Support

Postman supports WebSocket connections for testing real-time APIs.

Connecting

  1. Open Postman.
  2. Click New → WebSocket Request.
  3. Enter your WebSocket URL (e.g., wss://your-api.com/ws?token=YOUR_TOKEN).
  4. Click Connect.

Sending Messages

  • Compose messages in JSON format.
  • Use the Send button to transmit.
  • View server responses in the message log.

Features

  • Save WebSocket requests for reuse.
  • View full message history.
  • Supports ping/pong and close frames.
  • Inspect connection status and events.

🌐 2. Browser Extensions

Popular WebSocket client extensions include:

  • Simple WebSocket Client (Chrome)
  • WebSocket King Client (Chrome/Firefox)

Features:

  • Easy UI to connect/disconnect.
  • Send/receive JSON or plain text.
  • View detailed message logs.
  • Support for custom headers and authentication tokens.

💻 3. Standalone Apps

  • wscat (CLI tool):
npm install -g wscat
wscat -c wss://your-api.com/ws?token=YOUR_TOKEN

  • Insomnia:

  • Supports WebSocket requests similar to Postman.

  • Good for combining REST and WebSocket testing.

  • Smart WebSocket Client (Chrome):

  • Lightweight extension with intuitive UI.

  • Supports multiple connections.

📝 4. Tips for Testing WebSocket APIs

  • Always test connection establishment before sending messages.
  • Validate error handling by sending malformed payloads.
  • Test reconnection by manually disconnecting.
  • Use timestamps or unique IDs in messages to trace flows.
  • Monitor network traffic with browser DevTools → Network → WS tab.

✅ 5. Summary

Tool Platform Key Features
Postman Desktop/Web Saved requests, message history
Simple WebSocket Client Browser extension Easy connect/disconnect
wscat CLI Lightweight, scriptable
Insomnia Desktop Multi-protocol support

🔚 Next Steps