HTTP 101 Switching Protocols is sent by the server in response to an Upgrade request header from the client, indicating that the server is switching to the protocol specified in the Upgrade header. This is the mechanism that enables WebSocket connections — the client sends an HTTP/1.1 GET with 'Upgrade: websocket' and 'Connection: Upgrade', and the server responds with 101 to confirm the protocol switch. After the 101 response, the connection is no longer HTTP; it speaks whatever protocol was negotiated.
Response includes the status code, standard headers (including Content-Type), and a small diagnostic JSON body describing the request and returned status.
Simulator URL (copy in the app after load — not a normal link):
https://httpstatus.com/api/status/101
Example request:
curl -i "https://httpstatus.com/api/status/101"