What is HTTP/3?

HTTP is an essential backbone of the Internet — it dictates how communications platforms and devices exchange information and fetch resources. In short, it is what allows users to load websites.

HTTP/3 is a new standard in development that will affect how web browsers and servers communicate, with significant upgrades for user experience, including performance, reliability, and security.

History of HTTP

After the first hypertext transfer protocol (HTTP) was released in 1991, subsequent iterations made websites faster without any changes to the underlying code.

New Features in HTTP/3

HTTP/3 will be the first major upgrade to the hypertext transfer protocol since HTTP/2 was approved in 2015.

An important difference in HTTP/3 is that it runs on QUIC, a new transport protocol. QUIC is designed for mobile-heavy Internet usage in which people carry smartphones that constantly switch from one network to another as they move about their day.

The use of QUIC means that HTTP/3 relies on the User Datagram Protocol (UDP), not the Transmission Control Protocol (TCP). Switching to UDP will enable faster connections and faster user experience when browsing online.

Why a New Version is Needed

QUIC will help fix some of HTTP/2’s biggest shortcomings, such as sluggish performance when a smartphone switches networks and decreasing the effects of packet loss.

Benefits of HTTP/3

• Faster connection establishment with QUIC allowing TLS version negotiation simultaneously with the cryptographic and transport handshakes.
• Zero round-trip time (0-RTT) for clients that have already connected to servers, skipping the handshake requirement.
• More comprehensive encryption with QUIC’s new approach to handshakes providing encryption by default.

Encrypting by Default

Requiring encryption within the transport layer has important implications for security. It means that the connection will always be encrypted, a significant upgrade from HTTP/2.

Availability of HTTP/3

While the standard is still in development, support for HTTP/3 can be initiated through browsers, operating systems, and other clients.

Challenges and Development

One potential hurdle for the new protocol is increased CPU usage. The IETF assembled the QUIC Working Group in 2016, and many organizations are involved in the development process.

Enabling HTTP/3 for Websites

Cloudflare enables website owners to turn on support for HTTP/3 without any changes to their origin.