WebSocket

Three strengths

• Updates as they happen. The page receives new information without having to keep asking the server for it. 2
• Two-way messaging. Messages can travel in both directions over a single open connection. 1
• Nearly every browser. About 97% of browsers worldwide support it. 3

What it is

The web was built on a simple routine: your browser asks for something, the server answers, and then the conversation ends. That's fine for reading an article, and awkward for anything live, like a dashboard, a chat or a notification. For years the workaround was polling, where the page keeps asking the server "anything new?" every few seconds. The standard behind WebSocket is blunt about polling: it says building live apps this way "has required an abuse of HTTP". It lists the costs: the server needs several connections for each user, and each message sent to the server carries extra header information. 1

WebSocket replaces the routine with an open line. A page and a server set up one connection, and then either side can send a message whenever it likes. 1 MDN, the web developer documentation run by Mozilla, describes it as a way "to open a two-way interactive communication session between the user's browser and a server". You can "send messages to a server and receive responses without having to poll the server for a reply". 2

It was standardised as RFC 6455 in December 2011, written by Ian Fette of Google and A. Melnikov of Isode, and published by the Internet Engineering Task Force, the body that sets the web's technical standards. 1 The protocol works in two steps: an opening handshake that starts the connection, then a simple way of packaging messages over it. 1 Browser support is now close to universal, at about 97% of browsers worldwide. 3

We choose it when a feature should feel live, because the person never has to refresh the page or wait for the next check.

How we use it

We use WebSockets for live features in the apps we build: dashboards that update as the numbers change, notifications that appear the moment something happens, and direct messaging between people inside an app. We've built in-app messaging this way into two of our mobile apps.

That's Software Development work, and it usually sits alongside React on the web or React Native on phones, with serverless code behind them. For you, it means a product that feels current and responsive, in keeping with our human-centred approach to software.

References

1. I. Fette and A. Melnikov, "RFC 6455: The WebSocket Protocol", Internet Engineering Task Force, December 2011. https://www.rfc-editor.org/rfc/rfc6455 (accessed 28 October 2026)
2. Mozilla, "WebSockets API", MDN Web Docs. https://developer.mozilla.org/en-US/docs/Web/API/WebSockets_API (accessed 28 October 2026)
3. caniuse.com, "WebSockets", browser support tables. https://caniuse.com/websockets (accessed 28 October 2026)