"Project Spartan" in the Windows Technical Preview build 10049

Today we’re excited to announce the availability of a new build for Windows Insiders with the first preview of “Project Spartan,” the new browser for Windows 10. You can learn more in Joe Belfiore’s blog post, “Introducing Project Spartan: The New Browser Built for Windows 10."

This build does not yet include all the changes we announced last week, so the new rendering engine can still be enabled in Internet Explorer under "about:flags" by selecting "Enable experimental web platform features." This will be removed in a future update.

Project Spartan includes some new rendering engine updates in this flight, which we’ll detail in future posts. Notably, we are excited to announce preview support for the <img srcset> attribute for responsive images.

You can try out Project Spartan yourself in the new build via the Windows Insider Program and share your feedback on Twitter at @IEDevChat and in the comments below. Feedback on the Web platform powering Project Spartan should continue to go to the Web Platform Suggestion Box, and we welcome your feedback on Project Spartan itself at the brand new Project Spartan Feature Suggestion Box. Let us know what you think!

Kyle Pflug, Program Manager, Project Spartan

Update 3/30/2015 at 6:00 PM: The original post erroneously stated that Internet Explorer can no longer access the new rendering engine in this build. This has been corrected to indicate that Internet Explorer can still enable experimental web platform features in about:flags, which will be removed in a future update.

Comments (47)
  1. Husam Humaidan says:

    Thank you very much. your hard work is really appreciated. keep the excellent work. I'll keep giving you feedback . updating now 🙂

  2. noname says:

    Project Spartan is Windows 10 only?

  3. Phan says:

    Yes is correct Project Spartan only windows 10 only

  4. Ben S says:

    Very excited thanks for the updates!

  5. warrens says:

    Thanks for the update…. looking forward to trying this out with our apps!  I have two questions regarding IE11 as shipped with Windows 10:

    1) Will it include the same standards improvements we've seen so far in IE11 for Windows 8.1, such as the WebGL conformance fixes shipped back in August?  

    2) Will the latest standards mode still be called "Edge" in the IE11 dev tools?  (Might make sense to rename this to "11" at some point when the IE team has reached a point where they'll be making no further improvements to MSHTML)

  6. Aram Koukia says:

    So Excited for Win 10

  7. Done with Windows 10 (a.k.a. the next Vista clone) says:

    Well, since Windows Technical Preview build 10049 (both, upgrade from previous build and fresh install from ISO) no longer works in a Windows 8.1 client Hyper-V VM environment (enhanced session keeps on disconnecting every few seconds) and build 10049 is buggy to death anyway (Microsoft really dares to deliver such a junk?), I'm done with Windows 10 (already wasted too much time with). Windows 8.1 Update 1 works just fine (a great start screen/charms/apps bar experience and quite stable on my Dell XPS 8700 i7 32 GB box), and even if Microsoft would pay for the upgrade to Windows 10, I do not expect Windows 10 being ready for production until EOL of Windows 8.1.

  8. GTX says:

    Can you please introduce colors to the browser user interface? The current vampire edition is nice, but the rest of the world love colors you know, colors with shades and style please, not the depressing stupid plain colors (the mao tze dung edition)

    Wish you good luck, you will need it, hundreds of people's hard work my get wasted because 4 stupid managers think they are vampires or something

  9. Greg says:

    Will Spartan disable activeX/Com based plugins except for acrobat, flash, and Silverlight?

    We need a compelling end of life reason to replace the many vendor products requiring dedicated activeX/com based browser hosted plugins.

  10. user says:

    i think your decition make win8 dilemma and wp7.8 backfire again: two choice to confuse user, and anti-accessable ux,

     and push them to webkit(blink) based browsers.

    the pratical way to upgrade ie user is:

    1. solidify ie11 as it is, at same time let edge browser(Spartan) compatable for all site.

    2. at least in first 1-2 release, edge browser in enterprise mode: let mshtml live in it's tab, same as ietab

    3. base on feedback, gradually deprecate compatible mode. as flash, do that as carefully or you'll lose share

    4. build edge browser control to work as current webbrowser(weboc) control(best in winrt api as wp8 phone .net api),

      or else your developers are forced to go to cef.

    5. webview is feature-poor, and it will always be as your doc says it not to provide full browser capabilities.

    6. put better win10 app web develper env the top proprity of your browser api list


  11. ところで says:




    Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/39.0.2171.71 Safari/537.36 Edge/12.0

    Mozilla/5.0 (Windows NT 10.0; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/39.0.2171.71 Safari/537.36 Edge/12.0


  12. NumbStill says:

    I tried using the RemoteApp to access Internet Explorer, but it does not work anymore.

    – Started it.

    – Double clicked on the Internet Explorer preview icon.

    – A blank window came up and an alert showed up –

    Stack overflow at line: 43

    – Restarted Windows.

    – Started it.

    – Let it update.

    – It started.

    – A blank window comes up with the same alert.

    Windows 7 SP 1 with Internet Explorer 8.

    Seems to be reported here (I added the above information there, too) –


  13. ところで 訂正 says:





  14. joe says:

    Wow, I just installed 10049 to try out Spartan.  It is so not ready for release.  It froze trying to render cnn.com.  IE is still a lot better and faster.  Will Spartan really be ready by the end of the year?  

  15. Stilgar says:

    Does Spartan have an extensibility mechanism to replace ActiveX or there is no option for plugins?

  16. mohamad atiye says:

    Dear microsoft spartan browser team,

    I would like to point out that me and many of the people i know still use google chrome only due to its native inpage translation…i live in russia now(i dont know russia  yet) so most of the sites i use should be translated for me to understand. I ask you to please make a solution for this. Thanks

  17. Andrey Oliveira says:

    Well it could be possible to do a search only in the content of the pages (not sites) that are a favorite. For this, the content of synchronized favorite pages could be indexed by Bing and linked to my account on a particular search session.

  18. Karl says:

    Spartan browser have Add-Ons.

    now Flash Player only.

    Are We develop Add-Ons By .Net Framework?

  19. Gary Steeles says:

    Re-posting from the last post…

    @MSFT The most important bit of info was missing from this (and all past posts). The codename for the new browser is "Project Spartan" but can we get some details on what the new name will be?  We need to start publishing documents for our Enterprise clients detailing which browser they need to use and which icon to use per app they are using (not all will be able to run in 100% Standards Mode due to flawed designs by original developers that leveraged IE-only technologies (wow – talk about instant technical debt!))

    Will it be called "Internet Explorer 12"? "Metro IE 12"? (oh please god not "Modern UI IE 12"?) or will just the "Project" part drop and become just "Spartan"?

    Please indicate soon as we will have clients updating to Windows 10 as soon as it comes out.

  20. Gary Steeles says:

    Oh, and now an additional question regarding this quote from the linked article: blogs.windows.com/…/introducing-project-spartan-the-new-browser-built-for-windows-10

    <quote>At the same time, we recognize that for some of our enterprise customers, it’s important they have the support they need and can continue to use Internet Explorer when and where they need it. This is why we will continue to make it easy for our enterprise customers to make Internet Explorer 11 the default browser via group policy. Internet Explorer 11 is supported on Windows 7, Windows 8.1, and Windows 10 for all customers, also providing a consistent platform that’s great for enterprise Web apps.</quote>

    This quote is very ambiguous – does this mean:

    A.) That whatever "Project Spartan" will be named – will **NOT** be manageable via Group Policy in the Enterprise?


    B.) That for IT departments worried about Spartan being the default browser, rest assured it can be set back to IE11?

    There is a massive difference between the 2 potential meanings.

  21. @Gary: They're saying (B), but I'd be surprised if there were really no options for GP control of *some* Spartan features.

  22. leoniDAM says:

    but the WebView control and the Windows apps written in HTML/CSS/JavaScript will use MSHTML.dll or EdgeHTML.dll?

  23. hAl says:

    As group policy control is vital for security purposes most business will likely not allow the use of spartan browser.

    We need IE11 (preferbly IE12) to use the edge rendering engine.

    You should better stop supporting the IE9 and IE10 rendering in stead of dropping edge rendering in IE

  24. meir weiss says:

    so I am reading Spartan w win 10 and msie 11 x alongside.

    I have not been able at all to upgrade windows since nov 2014 a major glitch  with win update

    I need to know that the upgrade to win 10 will correct all this problem with win 8.1x

    and msie 11x

    or reformat hdrive to win 8.1 64 bit now [ my last resort]

    Iafter upgrading I need complete win update smooth upgrades or i'll be major frustrated, as I am now

  25. Please make Spartan installable/runnable on older operating systems says:

    Please… please… please… make Spartan run on older operating systems… At LEAST Window 8.  It will take forever for IE to fade away with XP, Vista, Win7, Win8, Win8.1 still in the wild.  I'm not suggesting delaying Windows 10 timeline for this.  When 10 is RTM, please work to get Spartan installers for older operating systems!  Otherwise there will be 10-15 more years of hacks and shims for backward compatibility.  Developing against evergreen browsers is only going to become a reality when the old machines with old Windows versions dilute the market share of IE to the point where nobody cares about their experience.  I'm hoping that the most popular sites will start forcing users away from IE versions as soon as possible.  Since you guys still seem to think that synchronizing your web browser versions with your operating system releases is a good idea, the only viable recommendations would be to install Chrome or Firefox and not Spartan.  So you're not just screwing over hundreds of thousands of web developers and wasting billions of man-hours of frustration/labor globally, you're shooting Spartan in the foot before it's even released.

  26. Husam Humaidan says:

    I just want tabs to be really separated and fluid when opening them. if I make any action on a certain tab like opening link then instantly try to navigate to another already opened tab the browser will hang for a moment until the first tab responding then it will switch to the other tab. this slows the user experience  and browser fluidity. this issue was exist in IE11 and it still in Spartan. thanks

  27. Stilgar says:

    I want what Husam Humaidan  wants. And I don't want a tab to be able to bring down the whole browser (yes it happens in IE even though it uses multiple processes)

  28. Feng says:

    Please add 'Sources' tab (same feature found in Chrome developer tools) to F12 developer tool!!!!!!!!!

  29. domin says:

    spartan still has a fundamental flaw:

    whenever I minimise the browser, the audio also fades and mutes.

    did no one envisage a scenario where the user listens to a podcast, and continues other work, without the brower window in the way?

  30. Alan Burchill says:

    How do i enabled my content on my web page to support reading mode?

  31. Otto says:

    seems the engine is still a lot MSHTML… eg. same offSetWith Performance Problem (between 60%-80% slower than webkit) like IE11 =>



  32. ie user says:

    Too radical to let spartan1.0 (unmature) to edge only and default browser

    and ie11 not upgradable in win10.

    you dont learn of all of wp7.8, windows rt etc.

    Let Spartan be edgehtml + mshtml(or lauch ie window when compatibal mode) and default browser

    Let Saprtan has a deskmode starter or enable  new instance and start and open as quick as ie11.

  33. aaa says:

    「Project Spartan」は開発コード…。

    "Officel name"はなに??

    早く名前を、Hurry up!!!!

  34. Kree says:

    You know, if Spartan is going to be exclusive to Windows 10, I'm kinda hoping that the least that the Windows 7 and 8 users get is a rendering engine upgrade for IE 11 (both MSHTML and Edge) but alas, that seems to be a pipe dream…

  35. Rob says:

    Webbrowser control must keep compatibel rendering or it wil break many existing applications however it also needs edge rendering to be usefull for developers in their future applications

    That is why it is preferable that Microsoft releaes a new IE12 and webcontrol with both compatibility as wel as edge rendering possibilities.

  36. noname says:



    Windows 10はUIや機能は、PC版とモバイル版(タブレット、スマホなどPC以外)と別にすべき。


    「Windows 10の新ブラウザSpartanも無駄な機能を搭載」


  37. Alex says:

    Will Spartan on desktop support IAccessible and would be possible to get  IHTMLDocument2 from IAccessible?

  38. Terrance says:

    So what is this new browser going to be called?  Seems like a pretty simple thing to explain to us I don't understand why you're holding back on this info?!

  39. Piotrek Koszuliński says:

    Do I understand correctly that the new rendering engine is now available as Project Spartan app (with the new UI) and in Internet Explorer 11 after enabling it in about:flags? Is it exactly the same engine?

    I'm asking because the build 10049 is so terribly unstable that I cannot check it myself and during the short moments when Project Spartan app worked it gave me different results than IE with the experimental features enabled.

  40. @warrens – Yes, IE11 will be in sync on Windows 8.1 and Windows 10.

    @GTX – The UI isn't final and we are definitely watching feedback – the best place to give suggestions on the Spartan interface is at windows.uservoice.com/…/285214-project-spartan

    @Greg – We'll be talking more about extensibility in Spartan in the coming weeks and at //Build.

    @NumbStill – thanks for the feedback, I've passed it on to the RemoteIE folks to investigate.

    @joe – This is our first preview flight so there's lots still in the pipeline both in Spartan and the platform it's built on. Please share your feedback through the smile icon in the Spartan toolbar or via the Windows Feedback app – we're watching feedback both on the app itself and any site compatibility problems.

    @Gary Steeles – We know you're waiting for the name – we'll announce it as soon as we can share. I promise it won't be "Modern UI IE 12" :). For your second question, "B" is the intended reading – IT departments can set IE11 as the default browser via Group Policy.

    @leoniDAM – Windows apps on Windows 10 will use EdgeHTML.dll.

    @domin – Background audio is a super important scenario! We're working on it but it's not ready in the preview just yet.

    @Piotrek Koszuliński – The new engine will only be available in Project Spartan. In the current preview builds you can enable it in Internet Explorer 11 (via about:flags), but that will be removed in the future. There are some differences between the capabilities of EdgeHTML.dll in IE11 vs. Spartan in 10049.

  41. Stanley R. says:

    @Kyle Pflug [MSFT] – can you elaborate on the group policy part? Will Spartan be managed by GP too? Or will there be no need because Spartan won't have silly stuff like "security zones" and ActiveX controls any more?

  42. Donovan says:

    I still don't quite accept Microsoft's justification of keeping IE from using the new EdgeHTML.dll rendering engine. As it is currently, it doesn't affect compatibility at all since it doesn't dynamically switch between engines – it requires a manual about:flags change, with the old one as default. I feel that it would actually be beneficial for IE to be able to utilise either engine – it allows it to be an effective application for compatibility and a modern browser. Of course, I'm just saying this because I happen to use IE as one of my main web browsers (out of choice – gasp!) and would be disappointed if it weren't properly supported anymore…and I'm not exactly keen on switching to Windows 10 just for Project Spartan. *Sigh*

  43. hide says:

    Does project spartan support UI Automation or MSAA?

  44. Marley says:

    In the preview of Spartan all popup windows that are opened ignore the positioning set in the window.open() call, as well as the width and height.

    The position is "auto-centered-ish" (which I think is ok) but the sizing is ~3/4 of the current screen height and ~3/4 of the current screen width.  While initially aesthetically pleasing for some windows it looks horrible when the popup was intentionally sized differently.  Most importantly the UI for the window has changed to be locked to a minimum size of ~23rds of the window height and ~1/2 of the window width. For several popups this looks horrible and is an odd UX issue.

    PS I'm well aware that popups are uncool… but sometimes they are the perfect solution to a problem and they are used extensively in 1,000's of enterprise web apps.

  45. Tamara says:

    I am having trouble  updating windows 10,  build 10041 to 10049. Please some body help…..

  46. JorgTheElder says:


    I would recommend you wait for the next build 10049 is unstable as hell.

  47. N2Q2 says:

    After reviewing  Project Spartan, came up with some PRO and Con.


    Users will like the quality of picture and plays vidios and Netflix very will.  With Windows 10 you are able to read the screens better when running GTX 980.  


    1.  There is really no menu you can not move your favorites from explorer or other browsers over to Spartan.  The favorite bar sits so low it seems to cut it off.  

    2.  To the normal user Spartan will not like it because they all got use to menu bars, status bars etc.  All other browsers have this.  You tried to clean it up but does not work well.  

    3.   It does seem some time that the sound goes up and down, however I believe this is windows 10 doing this.  

    When it come down to it you will be lucky to have 1 percent use Spartan it has a very long way to go.

Comments are closed.

Skip to main content