Switching Protocols

1xx · Informational

The requester has asked the server to switch protocols.

What does HTTP 101 Switching Protocols mean?

Sent in response to an Upgrade request header, indicating the server is switching to a different protocol — most commonly when upgrading an HTTP connection to a WebSocket.

1xx responses are provisional — they tell the client the request was received and the process is continuing. They are rarely seen directly in everyday web development.

When you'll see HTTP 101

Upgrading an HTTP connection to a WebSocket
Switching to HTTP/2 over cleartext (h2c)

Example

GET /chat HTTP/1.1
Upgrade: websocket
Connection: Upgrade

→ HTTP/1.1 101 Switching Protocols

Related 1xx status codes

100 Continue

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