HTML5 means different things to different people. You could argue that HTML5 only includes features that are defined in the W3C HTML5 specification. Or you could argue that it includes every specification, draft or experimental feature that is added to browsers in the last couple of years. We decided to take the middle ground and split the test into three parts: the official HTML5 specification, specifications that are related to HTML5 and some experimental new features that are extensions of HTML5.
Many of the related specifications were at one time part of HTML5. During the development of the specification they were moved to separate specifications.
We would love to add new browsers, but not all browsers are eligible. First of all we only accept browsers that are publicly available, either in beta form or a final release. We do not accept scores for internal development builds. Secondly we only accept browsers that are available in English. We want to check browsers before including them and unfortunately we do not speak Chinese, Japanese, Korean or Russian. And finally we only accept browsers which have a unique score. There are many browsers that are forks or modified versions of Chromium or Firefox. Similarly there are many browser that embed Internet Explorer or Webkit as provided by the operating system. These browser do not qualify. For comparisons, simply choose the original browser on which the browser was based instead.
We retain the right to make exceptions to any of the rules above and to remove or refuse any browser we deem necessary.
We cannot distinguish between a browser that supports a particular feature and a browser that lies about supporting that feature. The only way to deal with these situations it to manually confirm the test results. And if a browser is found to be overly confident about claiming support for certain features we can put that browser on a blacklist. That means that that even though the browser claims to support a particular feature, we ignore what the browser says and do not give any points. This is usually just a temporary problem and once the browser has been fixed we will remove the new version from the blacklist.
Claiming to support a feature which isn't working is not just causing problems for the reliability of the test results, but there are other real-world problems. For example if you claim to support WebGL, a website make decide to serve WebGL content. If your browser does not support WebGL, the website may fail in an uncontrollable way. If you correctly denied support for WebGL, the website may have served alternative content that would work in your browser. If you claim to support features that you don't, you are breaking the web.
If we find that a browser is structurally lying about which features they support - deliberately or not - we will usually give a warning to the developers of the browser and if the problem hasn't been fixed in the next version we will remove the browser from the 'other browser' and 'compare' pages and/or give other penalties. In extreme cases we may block the browser from showing test results and show a warning instead.
Unfortunately, in two very specific cases we are forced to use browser sniffing. The first case is
which was not supported on many older mobile devices. Yet almost all mobile browsers claim to support
Fortunately modern mobile devices are starting to support
contentEditable, but this left us with a problem. We
cannot reliably detect if a browser has proper support. The only way around this is to use a whitelist of
mobile browsers that do support this feature, otherwise you risk awarding points to mobile browsers that they
do not deserve. The second case is drag and drop, which is also not supported on mobile phones and tablets.
Please open a new issue on Github when you believe a browser should be included on the whitelist.
Each time you visit this website your score and test results are logged on our servers. We also store the user agent of your browser which contains information about the browser, operating system and device you are using. The collected information is solely used to generated anonymized reports about HTML5 support in browsers and improve the quality of our software.
We do not store cookies in your browser, but we do use several external components that do, including: Google Analytics, BuySellAds, Facebook, Twitter and Google+.