WebSocket isn't always the right tool. Here's an honest comparison to help you choose the right real-time technology for the job.

The Three Options

Option 1 — WebSocket

Full-duplex, persistent TCP connection. Both sides can send at any time.

// Client
const ws = new WebSocket('wss://api.example.com/ws');
ws.onmessage = (e) => console.log(e.data);
ws.send('Hello!'); // client can also send

Pros:

• Full-duplex — both sides send at any time
• Lowest latency (binary frames, no HTTP overhead per message)
• Native binary data support
• Works in all modern browsers

Cons:

• More complex server setup
• Stateful — harder to scale horizontally
• Some corporate firewalls/proxies block ws://

Use when: Chat, games, live collaboration, trading, multiplayer apps, anything bidirectional.

Option 2 — Server-Sent Events (SSE)

HTTP-based one-way push: server streams events to client over a persistent HTTP connection.

// Client — just one line!
const es = new EventSource('/stream');
es.onmessage = (e) => console.log(e.data);

// ONLY server → client
// Use fetch() for client → server