Microsoft Edge improves HTML5 support on Windows 10 build 14901

While users are still installing the Anniversary Update on their computers, it doesn't mean that development of Windows 10 has concluded. Microsoft is already working on "Redstone 2", and the first test preview for the next version of the operating system is now rolling out to Insiders.

Windows 10 build 14901 is now available for Insiders with PCs enrolled in the Fast ring. According to the company, the new version doesn't introduce any significant changes, as the development team is currently making structural improvements to OneCore (the shared "heart" of Windows across devices) to get the operating system ready for new features. However, if you look closely, you'll see some real improvements coming to Microsoft Edge.

Improvements for Microsoft Edge on build 14901

Starting with Windows 10 build 14901, Microsoft Edge version number jumps from 38.14393 to version 39.14901.

Microsoft Edge version 39 doesn't bring new visual elements or features but compared to version 38 there some exciting new changes inside the Developer Settings, which you also know it as the about:flags page.

Under Composition, you can now select between Selfhost, Stable, and Canary composition engines, which replaces the Windows.UI.Composition option.

In the WebRTC section, we're also seeing that Microsoft is adding a new option to enable WebRTC 1.0 in the web browser. (For those unfamiliar, WebRTC stands for "Web Real-Time Communication", and it's a web standard that allows support voice, video, text, and peer-to-peer file sharing without the need for an extension.)

Then there is the new "Service Workers" feature, which allows Microsoft Edge to support rich offline experiences, push notifications, background sync, cash storage, and other functionalities that usually would require a native application.

The currently available options in the experimental settings are:

  • Enable service workers
  • Enable push notifications
  • Enable background sync
  • Enable service worker cache storage

Finally, this new version of the web browser also includes a new network option called "Fast Networking," which allows you to enable fetch based network stack.

Improved HTML5 support

Although seeing more web standards coming to Microsoft Edge is always good news, perhaps what's more important is how well these new features make Microsoft Edge score on HTML5test.

An HTML5test score helps to define how well a web browser supports HTML5 standards and many other web specifications. Microsoft Edge version 39 scores 500 out of 555 possible points, which is very impressive. However, it's important to note that the high score is only possible when certain experimental features are enabled on Edge.

Out of the box, Microsoft Edge version 39 scores 460 points, which is 32 fewer points than the 492 points Google Chrome scores with the default settings, but turning on specific experimental features boost the browser to an impressive 500 points.

If you're running Windows 10 build 14901, you can test the score by turning on all the experimental features in the about:flags page, but making sure you leave the following options disabled:

  • Allow Adobe Flash Player localhost loopback
  • Allow unrestricted memory consumption for web pages
  • Disable Pointer event interfaces
  • Use legacy set internal behavior

Also, you must configure the four combo boxes with the following options:

  • Composition engine to Canary
  • Enable touch events to Only on when a touchscreen is detected
  • Fire compatible mouse events in response to the tap gesture to Only on when touch is enabled
  • Enable VP9 video format to Automatic

Then restart the browser and go to to see the test results for Microsoft Edge.

It's important to point out that the HTML5test is not a speed test. It's only a test that checks what HTML5 and other web standards a particular web browser supports.

What do you think about the new improvements on Microsoft Edge for Redstone 2? Tell us in the comments below.

More Windows 10 resources

For more help articles, coverage, and answers on Windows 10, you can visit the following resources:

Mauro Huculak

Mauro Huculak is technical writer for His primary focus is to write comprehensive how-tos to help users get the most out of Windows 10 and its many related technologies. He has an IT background with professional certifications from Microsoft, Cisco, and CompTIA, and he's a recognized member of the Microsoft MVP community.

  • Very nice! It's great to see that Microsoft has finally adopted the W3C standard of HTML5 and JavaScript standards that are found in Chrome and Firefox. Edge is proving more and more to be a formidable choice in the browser world. I now don't use any other browser because of its ease-of-use.
  • Microsoft has always supported the HTML5 and JavaScript standards. In fact, many of the features of HTML5 and CSS3 originate from Microsoft. Sure they didn't support all things, but the things they do support, they supported equally as good as Chrome and Firefox or better. Mainly Chrome often goes its own way instead of following the standards.
  • Are you ignoring ie history? Posted via the Windows Central App for Android
  • History changes. And regarding this your history is quit a while ago.
  • I don't think you know what you're talkin' about. IE is considered 'bad' because it's outdated. It was more than good at it's time. Another thing you may hear is that IE follows no standards etc. and that's true from one side but ultra false from the other. Namely, IE existed before standards were a thing, especially a thing that you are supposed to follow. The browser wars were only begining. IE actually helped the web scene by making it's own kind of standards - filling holes were needed (with their own implementation). And the problem arose when people didn't care to switch to more recent versions of IE or even other browsers, which forced web devs to still develop sites for both the official standards, which started to get traction, and the old custom IE 'standards', which made progress and further standard adoption slow and painful. Atleast in my eyes IE and MS did a great job.
  • No, not ignoring IE History but Edge is a completely different browser. Edge supports those parts of HTML5 that are part of the standard not the experimental parts that Chrome and Firefox also support. Edge also doesn't support the proprietary parts that Chrome and Firefox have. Let's also remember that Edge is the only browser that can stream from Netflix in 1080p, Chrome and Firefox can only manage 720p.
  • Really? I didn't know Chrome and Firefox can't do 1080p streaming for Netflix. It they can't do it for Netflix, how about YouTube 1080p? What makes it possible got Edge?
  • I would assume it has something to do with the codec used for streaming, YouTube can be streamed in 1080p by Edge, Chrome and Firefox but I suspect that's due to HTML5
  • Even going by history, the statement is accurate.   ​This 'disconnect' is with IE5 and IE6, which when released were MORE standards compliant than any other browser.  Here is where the politics of Sun/IBM/WeHateMicrosoft screwing with the Web kicks in to the story. IE5 and especially IE6 included several 'features' pending W3C approval, as Microsoft had been one of if not the largest contributor to HTML/CSS/XML features in the late 90s. Instead of the features 'supported' in IE being approved, they were rejected from the W3C from protest by Sun/IBM/etc.  They argued that Microsoft was trying to TAKE OVER the web. (Which was BS, as most of the features that Microsoft had submitted and had rejected in 1999/2000/2001 were later added, but using a slightly different syntax.  The irony is that many of the features that make CSS3 and HTML5, are features that Microsoft originally submitted over 10 years earlier.  (This is a fine example of how Politics in the Tech Industry hurts everyone.) Where IE6 lost it 'standards' compliance, as many businesses built Intranet and internal software website using the features of IE6, meaning Microsoft could not just remove them.  (Which is why IE7/8 had the IE6 compatibility mode for businesses as they also tried to move towards official standards.) ​It was not that IE6 had less features or was not complying with W3C on purpose, it was it had 'more' features that were expected to be approved and implemented.  (Imagine all the HTML5 features in Chrome that are not 'official' and are just 'pending' being removed, or implemented differently virtually overnight. Chrome would find itself in the same place IE6 did.) I can still remember reading an article about AJAX around 2004/2005, and how wonderful it was, and how it was too bad that when Microsoft submitted the idea over 5 years earlier, it was rejected and ignored outside Microsoft. ​There are also things like their XML technologies and XHTML and on and on that are all now a common part of the web, but were Microsoft Proprietary for many years, and implemented slightly different in IE6, making IE non-standards compliant.  ​Remember that the biggest argument against IE was that it included too many features that 'purists' argued should not be in HTML. You know really OUT THERE concepts like dealing with installable fonts, something that is now a part of the official W3C standards. (At that time, the anti-Microsoft websites would have IE display pages in WingDings, which would look normal on Netscape as it did not know how to handle the tags.)
  • So easy to use it can't even import my bookmarks. Lol.
  • Microsoft Edge sucks... I really wanted it to be good... But, the browser is slow and freezes up a lot.  I hate google as a company, but chrome is leaps and bounds better than edge, heck even firefox is better than edge by a long shot... And Chrome like 99% of browsers is really simple to use as well... What browser is difficult to use?
  • Now that's an article that merits our respect
  • Agree 100%. Neutral article very detailed and I have the feeling this guy knows what he's talking about.
  • I hope they add zoom memory sepcific to every websites. It is awful that all websites are shown with the same zoom page.
  • Shhh. Don't let the score out of the bag.  Google will now work harder!
  • Which would be a good thing. Competition is good, it drives innovation, it drives prices down. Thats why I don't understand the hard of thinking people on here who want Windows Mobile to die. It would make all of us worse off.
  • Well, lately Chrome is going backwards. So working harder that way would be a bad thing ;)
  • idk... Edge is actually slower on my SP4 with ABP extention, than edge was on pre-aniversarry update version of windows...
  • This is why people wanted them to implement the Ad-Block the way Opera did - directly into the browser.  Or, at least add TPL support to Edge.  Those Add-Ons don't come without a cost. I use Opera as my main browser on Windows.  Edge simply doesn't perform well on my AMD APU, and that's without Add-Ons.  Tab Hangs, Forced Reloads ("This tab has stopped working."), absolutely attrocious performance on pages with lots of images, broken comment boxes and text fields, choppy scrolling, etc. I reckon this stuff is all optimized with a[n extremely] heavy bias towards Intel. Will upgrade to a MacBook Air so I just don't have to ever worry about this kind of stuff.
  • It makes sense to you to get a MacBook to avoid a bias towards Intel..?
  • Better make the best browser on the planet because mobile web is becoming the future of W10M. :/
  • And how about the stability and page load/response time when accessing page using Edge on build 14902? Anybody has the issues out there?
  • Out of the box, Microsoft Edge version 39 scores 460 points, which is 32 fewer points than the 490 points Google Chrome scores with the default settings
    Admittedly I'm not the greatest at math, but 490 - 460 = 30, not 32...
  • Thanks for catching that typo. Chrome has an score of 492, not 490, that's why 32. Fixed!
  • My SP3 is absolutely flying on this build compared to the anniversary update. I did clean install of the anniversary, that was nice but this is great. If this is the track RS2 takes from first impression then I am looking forward to this year. Nice.
  • Wow, that's interesting. It must be blazing because anniversary is pretty damn fast in itself!
  • Edge is really good in Anniversary update. Before that, it was unresponsive and slow on my old laptop, whose specs aren't good..But now it runs better than my office laptop, which is high end laptop..I am waiting to update my office laptop to Anniversary update and edge will completely replace Chrome in it..
  • Great article and good to see Edge making good progress
  • Edge really is becoming an excellent browser. I find my myself using others less and less.
  • I don't know much about browsers, all I care about is when Chrome is loosing the 1st position and Edge takes the Crown.
  • As much as I love Edge, there is a bug in the HTML5Test that causes both ORTC and WebRTC to award 15 points, however, if both are supported, only 15 should be awarded in total, Edge is receiving 30 points. The real score with flags enabled is 485.
  • Tried using Edge to stream Olympic events. Encountered freezing which made it a less than desirable event. Switched to the latest version of Firefox. After installing Flash, it was much better, although not perfect either. Now that I am on a FIOS wireless 75/75 connection, so it is fair to say that the problem is not with my network connection.
  • I'm really curious about this service workers feature allowing push notifications etc. It almost sounds like there's a future that will no longer require mobile "apps", as the browser will be able to do all the things an app can do.
  • If edge would get a decent way of organising and browsing favourites I might actually use it again. I really hope extensions will help to improve this, because I doubt MSFT ever will ... smh
  • Great to see WebRTC coming along. Might be able to finally go all in on Edge for my roll20 gaming.
  • It's 490 out of 555 afterall.
  • I just want ad blocker
  • ABP does a pretty good job in the anniversary update
  • I hope that this update solves this problem:
  • I want an option to click to play html5/Flash videos. Otherwise I ain't using it.
  • I really want edge to be all in one browser. However good the score is for the browser I still use chrome for many sites which simply won't load on edge or just keep reloading automatically. Many a times browser won't open the pdf from website. I really appreciate the effort but I guess backward compatibility is also important coz not every site is on html5. My two cents
  • I ditched google chrome and replaced it with MS Edge, it still need to improve. I have Firefox alternative
  • Dude this improvement makes edge so usable it's not even close. They are really bringing win10 along! Posted via the Windows Central App for Android
  • I liked the 'cash' for 'cache' typo. I now try to use Edge exclusively on all my devices.
  • Edge is shaping up very well. It's my default browser right now. Only thing that sometimes sends me to chrome is certain rarely used extensions
  • Microsoft have tools for converting extensions to Edge from Chrome
  • Good news!
  • I still can't get HTML5/CSS3 to render correctly.  Using Chrome instead.  I like Edge, using it for pretty much everything else.
  • Hmmm... I tried to make the suggested changes, but I can't get Edge to score more than 460. I've make sure that Edge has been restarted by restarting the system.
  • The changes only apply on build 14901, I assume that's what you are using?
  • Verry verry nice!! ​ when i do the same settings in ''about:config'' im only get 485   when i enable ALL FLAGS the same.. who's get the 500 html5 points ?? which options do i need to enable?
  • also works on mobile :) score is 469
  • This ​is nice and all, but I sure freaking hope we don't have to wait for another mega-update to get some Edge improvements. It's sooooo close to being a great, every-day browser for me but the reliability issues are absolutely killing me.