Google has announced giving up SPDY after HTTP/2.0 has integrated the protocol and its standardization is in its final stages.
The Internet has run mostly on HTTP/1.1 since its standardization in 1999 as RFC 2616, a protocol that was later updated or made obsolete by 10 other newer versions of the standard. But some considered that there was room for improvement especially regarding its performance. Google was one of them, announcing the SPDY protocol back in 2009. Usually such an attempt has few chances to succeed because of the vastness of the Internet, but Google had one weapon to make it work: Chrome. They made their own websites and Chrome support SPDY, enticing users with better performance and putting pressure on other browser makers and websites.
Currently, SPDY is used by 3.4% of over 1.2B websites worldwide, according to W3Techs, which is not an important percentage, but among those are some of the largest websites including Google, Facebook, Yahoo!, Twitter, YouTube, Wordpress, etc., making the number of pages served daily over SPDY an important share of all pages.
The IETF HTTPBIS Working Group responsible for the standardization of HTTP/2.0 made SPDY a starting point for a discussion back in 2012, but initially they did not intend to fully adopt it. Microsoft had their own proposal called HTTP Speed+Mobility. Three years later it turns out that SPDY has won and it has been adopted by the HTTPBis WG for HTTP/2.0, being in the “Last Call” status in the standardization process.
As a result, Google has announced the retirement of SPDY by early 2016, implementing instead HTTP/2.0. It’s more of a name change for Google websites and Chrome rather than a protocol change. The latest Chrome 40 has a SPDY/4 flag that can be enabled by those interested in testing HTTP/2.0. Google is also removing support for NPN in favor of ALPN in Chrome, suggesting developers to use the latest TLS extension.
HTTP/2.0 is currently working with or without flags in Firefox, Chrome, Safari, Opera, iOS Safari, Chrome for Android, and IE 11 on Windows 8, according to CanIUse. The Windows 10 Preview also has it enabled in its browsers. Apache, IIS on Windows 10, and nginx have implemented SPDY 3.1 or 4 (HTTP/2.0). It remains for website admins to upgrade their servers.