How WebSockets Work

A persistent two-way connection for server-pushed updates

Reviewed by Abhijith N M · 24 October 2026 · Editorial standards

The Simple VersionNo jargon

A WebSocket starts as an HTTP request with an Upgrade header, then switches to a persistent connection. Both sides can send messages at any time without a new request. That is useful for chat, collaborative editing, live scores and dashboards. It is not automatically better than HTTP. You lose ordinary request/response semantics, caching and simple load balancing. You also need heartbeats, reconnect logic, backpressure and a plan for proxies that drop idle connections.

How WebSockets Work — Visual Breakdown

flow

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Browser

WebSocket Server

Sequence of Events

Why It Matters in Production

Use WebSockets when the server must push frequent, low-latency updates and the client must also send messages on the same channel. For one-way updates, Server-Sent Events are simpler and reconnect automatically. For infrequent updates, polling is often good enough and much easier to operate. At scale the hard parts are connection state, fan-out and authorization on every message. Sticky sessions or a shared pub/sub layer are usually required. Design for reconnects and missed messages from day one.

Implementation & Syntax

Read-only example

🐍Python

# FastAPI WebSocket example
from fastapi import WebSocket

@app.websocket("/ws/chat/{room_id}")
async def chat(websocket: WebSocket, room_id: str):
    await websocket.accept()   # Open the connection
    try:
        while True:
            # Wait for a message from the client
            data = await websocket.receive_text()
            # Broadcast to everyone in the room
            await broadcast(room_id, f"Message: {data}")
    except WebSocketDisconnect:
        print(f"Client left room {room_id}")

Quick Concept Check

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What HTTP status code signals a successful WebSocket upgrade?

Related Concepts

Complementary topics

TCP vs UDP

What is HTTPS?

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Written and edited by the nexGenCoders team. Spotted a mistake? Tell us and we will fix it.