WebSocket Test Client: Ultimate Guide for Debugging & Testing in 2025

Introduction to WebSocket Test Clients

Understanding the WebSocket Protocol

How WebSockets Work

Real-Time Data Use Cases

• Financial tickers and crypto markets
• Multiplayer games
• Live sports scores
• IoT telemetry dashboards
• Collaborative document editing

Importance of Testing WebSockets

Types of WebSocket Test Clients

GUI-based WebSocket Test Clients

CLI-based WebSocket Test Clients

When to Use CLI vs GUI WebSocket Test Clients

• GUI clients: Great for manual testing, debugging, and exploring message flows interactively.
• CLI clients: Ideal for automation, rapid checks, or integrating with scripts and other developer tools.

Setting Up a WebSocket Test Client

Installing CLI Clients (wscat, ws, wsc)

wscat via npm

1npm install -g wscat
2

ws via npm

1npm install -g ws
2

wsc via Go

1go install github.com/recws-org/wsc/cmd/wsc@latest
2

Using Online WebSocket Test Clients

• WebSocket King

  offers a free, browser-based websocket test client with advanced features.

• robtaussig.com/socket

  provides a simple online websocket tester for quick checks.

Choosing the Right WebSocket Test Client

• For developers needing automation: CLI tools like wscat or wsc are best.
• For quick, visual debugging or demos: GUI tools such as WebSocket King excel.
• For team collaboration or sharing test cases: Online tools are highly accessible and platform-independent.

Hands-On: Testing WebSocket Connections with WebSocket Test Clients

Connecting to Public Echo Servers

• ws://echo.websocket.org (may be deprecated in 2025)
• wss://echo.websocket.events (secure, recommended)

Using wscat (CLI)

1wscat -c wss://echo.websocket.events
2

```

Using WebSocket King (GUI)

1. Open

   WebSocket King

2. Enter the server URL: wss://echo.websocket.events
3. Click "Connect"
4. Observe connection status and message logs

Sending and Receiving Messages

Sending Text Messages (wscat)

1> Hello, WebSocket!
2< Hello, WebSocket!
3

Sending JSON Payloads (wscat)

1> {"type":"greeting","message":"Hello from wscat"}
2< {"type":"greeting","message":"Hello from wscat"}
3

Sending Binary Data (Node.js Example)

1const WebSocket = require('ws');
2const ws = new WebSocket('wss://echo.websocket.events');
3ws.on('open', function open() {
4  const buffer = Buffer.from([0x01,0x02,0x03]);
5  ws.send(buffer);
6});
7ws.on('message', function incoming(data) {
8  console.log('Received:', data);
9});
10

Using WebSocket King for JSON/Binary

• Paste JSON into the message box
• Choose "Send as Binary" for binary files
• View hex or JSON-parsed responses in the GUI

Advanced Features in WebSocket Test Clients

Authentication & Security

Secure Connections (wss://)

Client Certificates (wscat example)

1wscat -c wss://secure.example.com -k --cert client-cert.pem --key client-key.pem
2

Custom Authentication Headers (wscat)

1wscat -c wss://api.example.com/socket -H "Authorization: Bearer <token>"
2

Custom Headers and Protocols

Passing Subprotocols (wscat)

1wscat -c wss://example.com/socket -s "chat,superchat"
2

Custom Headers (wsc)

1wsc -u wss://example.com/socket -H "X-API-KEY: abc123"
2

Best Practices for WebSocket Testing with WebSocket Test Clients

• Security: Always use wss:// in production, validate server certificates, and avoid exposing sensitive tokens in public tools.
• Load Testing: Use CLI tools to script multiple parallel connections and stress-test your server under load.
• Debugging: Inspect raw frames, use verbose output, and log all sent/received messages to diagnose issues.
• Automation: Integrate CLI websocket test clients with CI/CD to catch regressions early.

Popular WebSocket Test Client Tools Compared

Conclusion