HTTP/2 Statistics - KeyCDN Report on HTTP/2 Distribution

By Brian Jackson
Updated on January 13, 2017
HTTP/2 Statistics - KeyCDN Report on HTTP/2 Distribution

KeyCDN officially released support for HTTP/2 back in October 2015 and is proud to be among the first CDN providers to offer the new protocol. Speed, stability, and security are of utmost importance to us as we analyze the most efficient ways to better deliver your content. After analyzing the data, we thought we would share with you some HTTP/2 statistics so you can see the distribution across our global network and across the web.

Total HTTP/2 distribution

The chart below reveals the distribution of the HTTP/2 traffic in percentage to the total HTTPS traffic delivered by KeyCDN. Back on October 11, 2015, it was just passing the 50% mark.

HTTP/2 Traffic - Updated October 11, 2015

And as of April 13th, 2016, HTTP/2 traffic has now reached 68%. So in 6 months there has been a 17% increase in HTTP/2 traffic and adoption.

HTTP/2 Traffic - Updated April 13, 2016

Top countries - Amount of HTTP/2 requests

The following list shows the percentage of HTTP/2 requests in relation to the total amount of HTTPS requests per country and a comparison over time. We pulled the top countries based on traffic volume.

CountryHTTP/2 in % (Oct 2015)HTTP/2 in % (Apr 2016)
United States46.8269.03
United Kingdom53.172.42

In total, HTTP/2 traffic across these countries has increased by 21.36% in the last 6 months.

Global HTTP/2 heat map

This heat map gives an overview in what region the HTTP/2 utilization is the highest. The heat map is based on the HTTP/2 percentage of the total HTTPS traffic by the top countries from October 2015.

HTTP/2 Heat Map - Updated October 11, 2015

And here is an updated heat map with April 2016 data.

HTTP/2 Heat Map - Updated April 13, 2016

Other HTTP/2 statistics from around the web

The HTTP/2 Implementations wiki page lists 90 different implementations (last updated June 2020), up from 36 back in March 2015.

HTTP/2 connections in Chrome and Firefox already surpass those of SPDY/3.1

New TLS + NPN/ALPN connections in Chrome (telemetry May 26, 2015)

  • 27% negotiate HTTP/1
  • 28% negotiate SPDY/3.1
  • 45% negotiate HTTP/2

9% of all Firefox (M36) HTTP transactions are happening over HTTP/2. There are actually more HTTP/2 connections made than SPDY ones. This is well-exercised technology.

- Patrick McManus, Mozilla

Important things to consider with HTTP/2

Is it time to finally migrate to HTTPS?

Back in 2014 Google announced that HTTPS is now a ranking factor and part of their algorithm. While it is a very lightweight signal, it is still there to help sites that are adopting Google's goal for HTTPS Everywhere. So before the release of HTTP/2, many website owners had to debate whether they would benefit migrating to HTTPS (SPDY) to take advantage of the ranking factor and also if SPDY was actually any faster.

While SPDY did improve site load times in some cases, due to so many different factors, lots of people also experienced slower load times with SPDY when compared to HTTP. However, this should no longer be the case with HTTP/2. Because of the new features with HTTP/2, users should see significant speed increases as CDNs and web hosts start adopting it.

So even websites that don't do any ecommerce transactions might want to now start thinking about migrating to HTTPS simply to take advantage of the performance benefits as well as the ranking factor. Also consider that in the future Google might put more weight on this ranking factor.

Speed increases

Load Impact put together a cool tool which does an approximation of how much faster your site would be over HTTP/2 vs HTTP/1. Basically they gather your assets, fetch them via their HTTP/2 server and do an analysis of approximate speed gains.

You can also check out this HTTP vs HTTPS test from Anthum which compares HTTP/1 vs HTTP/2. This is a good example of the power of parallelism with HTTP/2.

The team at HttpWatch saw speed increases of 20% when comparing HTTPS vs SPDY/3.1 vs HTTP/2.

HTTPS Page Load
SPDY/3.1 Page Load
HTTP/2 Page Load

We also found that HTTP/2 was consistently faster than SPDY even though its response messages were often larger. The advantage was probably due to the smaller GET request messages produced by HPACK compression.

- HttpWatch

No more concatenation or obsessing over HTTP requests

In the past, we have stressed the importance of concatenation and the importance of reducing the number of HTTP requests your site makes. With HTTP/2, these techniques become less important and shouldn't be necessary, because one of the main goals of the protocol is to reduce the marginal overhead of new requests. So in the future we will be discussing optimizations specifically for HTTP/2.

HTTP/2 also includes other improvements such as being able to request multiple items over one TCP request and better header compression. You read about all the benefits in our support article on HTTP/2.

Remove domain sharding for HTTP/2

Domain sharding is a technique for splitting resources across multiple domains so that resources can be downloaded by the browser simultaneously. With HTTP/1, domain sharding was used to enable higher parallelism, but with HTTP/2 this can actually have a negative impact on performance. If you users are all using modern browsers then it is recommended to remove domain sharding. HTTP/2 can automatically combine connections for you if the following conditions are met.

  1. TLC certificate is valid for both hosts
  2. Hosts resolve to the same IP


openssl s_client -connect | openssl x509 -noout -text | grep DNS

DNS:*, DNS:*, DNS:*, ...

One great metric around that which I enjoy is the fraction of connections created that carry just a single HTTP transaction (and thus make that transaction bear all the overhead). For HTTP/1 74% of our active connections carry just a single transaction - persistent connections just aren't as helpful as we all want. But in HTTP/2 that number plummets to 25%. That's a huge win for overhead reduction.

- Patrick McManus, Mozilla.

Most browsers only support HTTP/2 over TLS (HTTPS) connections

It is important to note that while almost all the modern web browsers support HTTP/2, most only support it over TSL connections. Which means if you want to see the benefits of HTTP/2, you will want to migrate to HTTPS, even though it is not a requirement of HTTP/2.

  • Chrome: Supports HTTP/2 only over TLS.
  • Firefox: Supports HTTP/2 since version 36, only over TLS.
  • Internet Explorer: Supports HTTP/2 in version 11, but only for Windows 10 and only over TLS.
  • Opera: Supports HTTP/2.
  • Safari 9: Supports HTTP/2.


As you can see HTTP/2 is here to stay and shows significant speed increases over that of HTTP/1 and SPDY. Even websites that aren't processing any secure information might want to look into migrating to HTTPS if performance is important to them. At bare minimum, all it takes is a free SSL certificate and then migrating your site to HTTPS. Aren't sure if your CDN or web host is running on HTTP/2 yet? Use our HTTP/2 test tool, or sign up for a free trial with KeyCDN and let us deliver your content via HTTP/2.

Have any additional thoughts on HTTP/2 performance, we would love to hear them below in the comments.

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