101 Switching Protocols

What is HTTP 101 Switching Protocols?

The 101 Switching Protocols status code is an informational HTTP response that tells a client the server has accepted a request to switch communication protocols.

It belongs to the 1xx Informational category and is most commonly associated with upgrading HTTP connections to protocols such as WebSockets.

Why Does 101 Switching Protocols Exist?

HTTP traditionally follows a request-response model where the client sends a request and the server returns a response.

Some applications require a persistent connection where both the client and server can continuously exchange data. Protocol upgrades allow an existing HTTP connection to transition into a different communication method.

The Upgrade Header

Clients request a protocol change using the Upgrade header.

GET /chat HTTP/1.1
Host: example.com
Upgrade: websocket
Connection: Upgrade

If the server accepts the upgrade, it responds:

HTTP/1.1 101 Switching Protocols
Upgrade: websocket
Connection: Upgrade

The connection then continues using the new protocol.

Common Uses

• WebSocket connections
• Real-time applications
• Chat systems
• Live dashboards
• Streaming communication

Why Does It Matter For DevOps?

DevOps engineers may encounter 101 Switching Protocols when debugging applications that rely on persistent connections.

• Reverse proxy configuration
• Load balancer behaviour
• WebSocket failures
• Real-time application connectivity

Summary

The 101 Switching Protocols response allows HTTP connections to upgrade into another communication protocol.

While uncommon in normal web traffic, it is an important part of modern real-time application infrastructure.