What is http/2
HTTP/2 (originally named HTTP/2.0) is a major revision of the HTTP network protocol used by the World Wide Web.
Since about 1997, the web has been mostly powered by HTTP/1.1. Back in the 90’s, the web had other needs than we have today. The new protocl version, HTTP version 2 or in short HTTP/2, has some much needed improvements in terms of speed, reliability and security.
I would strongly recommend you to upgrade your webserver to also support the HTTP/2 protocol.
Differences from HTTP1.1
Similar to SPDY, using HTTP/2 does not require any changes to how web applications currently work however, applications are able to take advantage of the optimization features to increase page load speed. According to the HTTP/2 home page, the high-level differences between the HTTP1.1. and HTTP/2 protocol include the following:
- HTTP/2 is binary, instead of textual
- It is fully multiplexed, instead of ordered and blocking
- It can use one connection for parallelism
- It uses header compression to reduce overhead
- It allows servers to “push” responses proactively into client caches instead of waiting for a new request for each resource
Overall, HTTP/2 means the server load will go down and the loading times for the end-user will go down drastically as well. And, since it results in a better user experience, it may be advantageous for SEO as well.
Comparison of SPDY3.1 and HTTP/2
Although SPDY and HTTP/2 both have the same goal in mind, there are key variations that exist between them. The following table outlines a few of the high-level differences between SPDY3.1 and HTTP/2
| SPDY3.1 | HTTP/2 |
| To use the SPDY protocol and take advantage of its features, SSL is required. | SSL isn’t required, however encrypted websites will see a boost in performance over today’s encrypted sites. |
| Multiplexing happens on one host at a time, known as single host multiplexing. | Multiplexing happens on different hosts at the same time, known as multi-host multiplexing. |
| SPDY’s stream-based compression method leaves a slight opening to protocol vulnerabilities. | Uses a fixed Huffman code-based header compression algorithm to further prevent attacks and shorten headers. |
| SPDY’s encrypted connections are fast however they do not use the ALPN extension. | Uses the ALPN extension which allows for faster encrypted connections by letting browsers and servers to decide which application protocol to use initially. |
HTTP/2 Support
Most major browsers fully support the use of HTTP/2. This means that if the website you are trying to access runs on an HTTP/2 supported server, your browser will be able to utilize its features. However, although the working group did not require the use of encryption for the new protocol, currently all major browsers only support HTTP/2 over HTTPS.
A more detailed history of browser versions that do support HTTP/2 can be found here.
| Browser | Supported |
| Chrome | Yes |
| Firefox | Yes |
| Microsoft Edge | Yes |
| Safari | Support limited to OSX 10.11+ |
| Opera | Yes |
| iOS Safari | Yes |
| IE | Supported in version 11, but only for Windows 10. |
| Android Browser | No |
How to check HTTP/2 support
Test HTTP/2 via command line
| 1 | — Using the command line, you can easily check if a website is using the newest HTTP/2 protocol. Using cURL, execute the following command: curl –http2 https://fallinlove.home.blog curl -sI domain -o/dev/null -w ‘%{http_version}\n’ => this will show which is current version. |
Online HTTP/2 test tools
| 2 | There are quite some tools available on the internet that let you enter the website and will show you if this site is using HTTP/2. KeyCDN: a free HTTP/2 online test tool to Verify HTTP/2.0 Support Akamai: test if your browser support HTTP/2. They also have a demo to compare the pageload time of a HTTP/1.1 versus the HTTP/2 version. CloudFlare: for a long time, CloudFlare is one of my favourite companies in terms of innovation and technology. They have a special subdomain to access their site in full HTTP/2 mode. |
HTTP/2 browser extension
| 3 | If you regularly want to get information about HTTP/2 of website you visit, it might be worth installing a browser plug-in. The HTTP/2 and SPDY indicator plug-in for Google Chrome is an excellent tool to visually indicate if the website you are currently using supports HTTP/2 or SPDY. |
Conclusion
HTTP/2 is without a doubt the direction the web is moving towards in terms of networking protocol that is able to handle the resource needs of today’s websites. While SPDY was a great step forward in improving HTTP1.1, HTTP/2 has since further improved the HTTP protocol that has served the web for many years.
Given you have a server that supports the HTTP/2 protocol, you can start serving content over this protocol to users that are accessing your content through a supported browser. For browsers that do not support HTTP/2, they will continue to be delivered content through the old protocol. Using the HTTP/2 protocol will help make websites faster and overall will improve the web’s user experience.
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