HTTP/3 and how it affects digital sustainability

HTTP/3 is the latest version of the Hypertext Transfer Protocol (HTTP) protocol. Distinctly different from the previous versions, HTTP/3 could offer faster and more efficient communication between servers and clients.

What is different about HTTP/3?

An important difference in HTTP/3 is that it runs on QUIC, a new transport protocol originally developed by Google in 2012. 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. This was not the case when the first Internet protocols were developed: devices were less portable and did not switch networks very often.

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.

While you could argue that this may not have a direct impact on digital sustainability, the new protocol’s methods of data transfer suggest that it can contribute by having lower latency and loading data more quickly in real-world usage when compared with previous versions.

By reducing the amount of data that needs to be transmitted, we are helping to reduce the energy consumption associated with data centers and other infrastructure that powers the internet.

How HTTP/3 affects digital sustainability

The way that HTTP/3 allows for more efficient use of network resources is by using techniques such as header compression, multiplexing, and server push.

What is header compression?

Header compression reduces the size of headers, which can make up a significant portion of the data transmitted between servers and clients.

What is multiplexing?

Multiplexing enables multiple requests to be sent and received in parallel over a single connection, reducing the need for multiple connections and reducing the overhead associated with establishing and maintaining connections.

What is server push?

Server push allows servers to send assets such as images and scripts to clients before they are requested, reducing the number of requests made by the client and reducing overall data transfer.

Potential issues with HTTP/3

Noted by Cloudflare, one potential hurdle for the new protocol is that it requires increased CPU usage for both the server and client. This will likely decrease in impact over time as the technology evolves. Of course, this is exactly what we try to avoid with digital sustainability. We want to decrease intensive CPU usage where we can. Not increase it.

Is HTTP/3 available now?

While the standard still looks to be in active development, support for HTTP/3 is actually very wide spread across browsers, servers and clients. Of course, there are likely more changes ahead for the standard, which has already gone through several implementations.

Chrome and Chromium based browsers use QUIC by default. Firefox added support in 2021, with Apple adding support to Safari in macOS Big Sur and iOS14 – though it has to be manually turned on. Cloudflare offers support for HTTP/3, and has done in beta since 2018. It is best to ask and check with your hosting company whether the server infrastructure they use supports it, and if not, when they may support it in the future.


HTTP/3 certainly should help to improve the speed in which data is transferred, as well as the security of that data. It could have a positive affect on digital sustainability. But, equally, as things continue to progress and change, it may also negatively affect it too. If it does indeed draw more power from the CPU at both the server and the client, this will not be the most sustainable process moving forward. Unfortunately, there doesn’t seem to be much or any data out there that displays this.

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