WebSockets definition
WebSockets is a protocol that keeps a single, long-lived connection open between a browser or app and a server, so either side can send messages at any time. Standardized as RFC 6455 in 2011, it enables real-time features such as chat, live dashboards, multiplayer games and collaborative editing without repeated HTTP polling.
How do WebSockets work?
A WebSocket connection starts as a normal HTTP request with an Upgrade header. If the server agrees, it replies with status 101 Switching Protocols, and the same TCP connection is then used for lightweight message frames in both directions. Secure connections use the wss:// scheme over TLS. Because headers are not resent with every message, overhead per message is tiny compared with making repeated HTTP requests.
Browsers expose the WebSocket API natively, and mobile platforms have mature clients. On the server, common choices include the ws library and Socket.IO for Node.js, Django Channels, Spring WebSocket and Go libraries, or managed services such as Pusher, Ably and Amazon API Gateway WebSocket APIs that handle connections for you.
WebSockets vs polling vs Server-Sent Events
Short polling asks the server for updates every few seconds, which is simple but wasteful and slow to react. Long polling holds each request open until data arrives, then starts again. Server-Sent Events stream updates from server to client over plain HTTP, ideal for one-way feeds such as notifications or streaming AI responses. WebSockets are the right choice when both sides send frequent messages, as in chat, games or collaborative editors. WebTransport, built on HTTP/3 and now supported in all current major browsers, adds multiplexed streams and unreliable datagrams for latency-sensitive cases, with WebSockets as the fallback for older clients.
Common WebSocket use cases
The common thread is that delay or polling overhead would hurt the experience. If updates arrive only every few minutes, or only flow from server to client, simpler options such as periodic fetching, Server-Sent Events or push notifications are usually cheaper to build and operate.
- Chat and messaging, including typing indicators and read receipts.
- Live order, delivery and ride tracking.
- Trading screens and live sports or auction updates.
- Collaborative documents, whiteboards and design tools.
- Multiplayer browser games.
- Live chat support widgets on websites.
- Live dashboards for IoT devices and operations centers.
Scaling WebSockets in production
WebSocket connections are stateful and long-lived, which changes how you scale. Each server holds thousands of open connections, so load balancers must support upgrades and long idle times, and a message for a user connected to server A may originate on server B. A publish-subscribe backplane such as Redis, NATS or Kafka routes messages between servers so every client receives its updates.
Clients must expect disconnections from mobile networks, sleeping laptops and deployments. Heartbeat pings detect dead connections, reconnect logic with exponential backoff avoids stampedes after an outage, and a resync step fetches anything missed while offline. Authenticate during the handshake and handle token expiry on connections that stay open for hours.
Example: live delivery tracking
In a food delivery app, the rider's phone sends a location update every few seconds over a WebSocket. The server publishes each update to a channel for that order, and the customer's app, subscribed to the same channel, moves the rider on the map in real time. Nexzem builds real-time features like this with reconnection, resync and fallbacks tested on poor mobile networks, not just office Wi-Fi.