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HTTPvsWebSocket

What is the difference between HTTP and WebSocket?

Updated October 6, 20262 min read7 differences

In short

HTTP is request-response: the client asks and the server answers once. WebSocket keeps one connection open so both sides can send messages at any time.

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HTTP

Hypertext Transfer Protocol

HTTP is the protocol that browsers, apps, and servers use to exchange web pages and data through a simple cycle of requests and responses.

Read the page on HTTP

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WebSocket

WebSocket is a protocol that keeps a single connection open between a browser and a server so both sides can send each other messages instantly at any time.

Read the page on WebSocket

HTTP and WebSocket compared

Aspect	HTTP	WebSocket
Pattern	Request and response: the client asks, the server answers	Messages in both directions at any time
Connection	Short exchanges; a connection can be reused for later requests	One persistent connection per client
Who can start	Only the client	Either side, once connected
Overhead per message	Headers on every request	A frame header of a few bytes
URL scheme	`http://` and `https://`	`ws://` and `wss://`
Caching and tooling	Caches, proxies and CDNs understand it	No HTTP caching; proxies must support the upgrade
Best for	Pages, REST APIs, downloads, form posts	Chat, games, live dashboards, collaboration

The difference, explained

HTTP works in rounds: the client sends a request, the server sends one response, and that exchange is over. It is the protocol behind web pages, REST APIs and file downloads, and it is stateless, so every request carries what the server needs, such as cookies or tokens. WebSocket is a separate protocol for a long-lived, two-way channel between a client and a server.

A WebSocket connection actually begins as HTTP. The client sends an ordinary GET request with an Upgrade: websocket header, the server answers 101 Switching Protocols, and from then on the same TCP connection carries small WebSocket frames in both directions. Either side can send a message at any moment, without the headers of a new request, until one of them closes the connection.

The difference matters when the server has news. With HTTP alone, the client must keep asking, through polling or long polling, which adds delay and wasted requests. With WebSocket, the server pushes each update the moment it happens, which suits chat, multiplayer games, collaborative editing and live dashboards. The price is state: servers hold many open connections, load balancers must keep them alive, and clients need reconnect logic.

A common misconception is that WebSocket replaces HTTP. Most apps use both: HTTP for pages, assets, logins and ordinary API calls, which benefit from caching and simple tooling, and WebSocket only for the real-time part. When updates flow only from the server to the client, Server-Sent Events over plain HTTP are often simpler.

Which one should you use?

Choose HTTP when…

The client asks for data when it needs it, as with pages and most APIs.
You want caching, CDNs and standard tools to work out of the box.
Updates are occasional, so polling or Server-Sent Events are enough.

Choose WebSocket when…

Both sides send frequent messages, as in chat or multiplayer games.
Updates must arrive within moments of happening.
You can run servers and load balancers that keep many connections open.

Polling over HTTP vs a WebSocket connection

HTTPjavascript

// HTTP: the client asks, here every 5 seconds, whether anything is new
let lastId = 0;
setInterval(async () => {
  const response = await fetch(`/api/rooms/42/messages?after=${lastId}`);
  const messages = await response.json();
  messages.forEach(showMessage);
  if (messages.length) lastId = messages.at(-1).id;
}, 5000);

WebSocketjavascript

// WebSocket: one open connection; the server pushes messages as they happen
const socket = new WebSocket("wss://chat.example.com/rooms/42");

socket.addEventListener("message", (event) => {
  showMessage(JSON.parse(event.data));
});

// The client can send on the same connection at any time
sendButton.addEventListener("click", () => {
  socket.send(JSON.stringify({ text: input.value }));
});

Readers ask

Is WebSocket faster than HTTP?

For frequent small messages, yes, because each message skips the request setup and headers that HTTP repeats every time. For a single request or a large download, HTTP is just as fast and easier to cache.

Does WebSocket use HTTP?

Only to start. The connection opens with an HTTP request that asks to upgrade; once the server agrees, both sides speak the WebSocket protocol over the same TCP connection.

Should I use WebSocket or Server-Sent Events?

Use Server-Sent Events when only the server sends updates, such as notifications or streamed AI answers; they run over plain HTTP and reconnect automatically. Choose WebSocket when the client also sends frequent messages.