It’s time to demand HTTP/2 for your site.

In May 2015 the first major revision of the HTTP spec in 14 years was finalized as RFC 7540 (IETF, 2015). This post is intended to help merchants understand the implications of this revision and how it affects their bottom line.

TL, DR (Too long, didn’t read).

  • Sooner is better
  • Some users don’t support it, but they will. Investing in HTTP/1.1 optimized design is short-sighted, and will have to be undone in future regardless.

HTTP (or Hypertext Transfer Protocol) is the protocol governing how your customers browsers interact with your e-commerce store. HTTP/2 makes several architectural changes in this connection such as:

  • Making page loads faster
  • Making it possible your development team to optimize your website for good development and good performance.

HTTP/2 started life SPDY, a protocol developed by Google following a series of experiments designed to make the web faster. Following the release of SPDY it was implemented in both servers and browsers and rapidly became a defacto standard. However, rather than allow the unofficial SPDY spec to determine the conversation around and future of the web, the IETF started work on creating a new HTTP spec, including many more parties in the conversation. The result is HTTP/2, a more thoughtfully constructed, polished protocol than either SPDY or HTTP/1.1.

What are the advantages?

  • Reduce the amount of data transmitted to our users (especially important for mobile).
  • Make more efficient use of the network connection.
  • Allow browsers to prioritize certain assets, decreasing page render time.
  • Allow better quality and more innovative application development.

Why should you care?

Implementing it sooner will reduce the amount of useless time (and cash) spent optimizing for HTTP/1.1.

If you’re curious, you can check out exactly who is using HTTP/2 (or QUIC, or SPDY) using the Chrome net-internals tool in the Chrome browser


What are the risks?

Support is growing, but not 100%. Currently, ~69% of all users support HTTP/2. Most notably, users who use the core browser for Android (not Chrome), iOS users who haven’t yet upgraded to iOS9, and Windows users who haven’t upgraded to Windows 10 all cannot access a website over HTTP/2. However, most servers (including Apache and NGINX) serve the website over both HTTP/1.1 and HTTP/2. This means that, while your users won’t experiences the benefits of HTTP/2, they will still be able to access the site as they do now.

The following browsers / devices support HTTP/2:

  • Chrome (Android, Windows 10, Windows 8, Linux)
  • Safari (iOS 9, Safari 10.11+)
  • Edge (Windows 10)
  • IE 11 (Windows 10)
  • Opera (Windows, Linux)
  • Firefox (Windows, Linux)

This invites the question: Should we optimise for HTTP/2? My option is yes. Most browsers are “Evergreen” (or self-updating), and the most recent versions of all browsers (except IE) all implement HTTP/2. While users who are still using older browsers only compatible with HTTP/1.1 will be served a slower version of your website, a rapidly growing majority of users will be using HTTP/2 and not optimizing for these users strikes me as a little short sighted.

It costs money. As with any new technology, there’s a cost to upgrade. It’s a much smaller cost than most development processes, and should be as simple as upgrading the server your website is being served off. It may take time for your development team to understand the HTTP/2 architecture well enough to take full advantage but the sooner you start this process the cheaper it will be in the long run.

How to start the conversation

It’s best to start the conversation with “What effect does site speed have on my customers?”. If you’re achieving a “time to glass” of 1s over HTTPS on 4G connections then, congratulations! You probably don’t need to do anything. If you don’t, it’s a worthy goal to strive for.

If you’re not sure how fast your site is, the Google PageSpeed Insights tool can be super helpful to determine whether your website is following the “best practices” of the day:

If you’re otherwise pretty sure that your speed ducks are in a row, place a ticket, schedule a phone call or otherwise start the conversation with “What is HTTP/2, and should we implement it”. I suggest you read a little beyond this article (the HTTP/2 FAQ in the references is a good place to start) before you start this conversation as the technology is new and you might catch your developers a little off guard.

Let me know what your experiences with H/2. Something awful backfired? I’d love to know about it — It’ll make me a better developer (clearly there’s something I didn’t know about).


Please be aware this post may change in the future.