# 101 Switching Protocols

> The server understands the Upgrade header field sent by the client and is switching protocols.

Source: https://apiguide.dev/status-codes/101
Class: informational
Defined in: RFC 9110, Section 15.2.2 <https://www.rfc-editor.org/rfc/rfc9110.html#section-15.2.2>
Updated: 2026-10-14

## What does HTTP status code 101 mean?

The 101 Switching Protocols status code indicates that the server is agreeing to switch protocols as requested by the client via the [`Upgrade`](/headers/upgrade) header.

## When to use it in APIs

This is the standard response returned during a WebSocket handshake. A client makes an HTTP request with `Upgrade: websocket` and the server responds with 101 to transition the TCP connection into a bi-directional WebSocket stream.

## How it compares to other codes

* **100 Continue**: Handles body transfer coordination, whereas 101 handles connection protocol upgrades.