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Microsoft Edge logo (2015–2019).svg
Screenshot of Microsoft Edge in Windows 10 showing the English Wikipedia main page rendered by EdgeHTML 17.
Screenshot of Microsoft Edge in Windows 10 showing the English Wikipedia main page rendered by EdgeHTML 17.
Stable release
Preview release
EdgeHTML Version 18.17746 / August 23, 2018; 2 years ago (2018-08-23)
Written inC++[2]
Operating systemWindows 10
TypeBrowser engine

EdgeHTML is a proprietary browser engine from Microsoft used in the Edge web browser. In December 2018, Microsoft announced that Edge is being rebuilt as a Chromium-based browser.[1][3] Despite this, the engine is still maintained for applications using UWP.[4]

Usage in Windows[edit]

EdgeHTML is a fork of Microsoft's Trident that was the engine of the Internet Explorer browser.[5] It was first released as an experimental option in Internet Explorer 11 as part of the Windows 10 Technical Preview build 9879.

EdgeHTML is designed as a software component to allow software developers to easily add web browsing functionality to their own applications. It presents a COM interface for accessing and editing web pages in any COM-supported environment, like C++ and .NET.[citation needed] For instance, a web browser control can be added to a C++ program and EdgeHTML can then be used to access the page currently displayed in the web browser and retrieve element values. Events from the web browser control can also be captured. It is also used to render WinRT-apps that are based on web technologies.

Release history[edit]

EdgeHTML release history
EdgeHTML Edge Release date Notes
12.0 none November 12, 2014 Initial version of EdgeHTML to be included as an experimental feature to Internet Explorer 11 to replace Trident 7.0 in next Project Spartan web browser, later renamed Microsoft Edge.
12.10049 0.10.10049 March 31, 2015 Introduced new features and came with the first version of Microsoft Edge.
12.10166 20.10166 July 9, 2015
  • localhost loopback became enabled by default. localhost could be toggled by navigating to about:flags.
  • Improved support for about:flags in locales other than en-US
  • Bug fixes
12.10240 20.10240 July 15, 2015 Initial public release. Contains improvements to performance, support for HTML5 and CSS3.
12.10525 20.10525 August 18, 2015 This release contains initial groundwork for Object RTC in Microsoft Edge.
12.10532 20.10532 August 27, 2015 New features such as Pointer Lock (Mouse Lock), Canvas blending modes, and new input types.
13.10547 21.10547 September 18, 2015 Edge HTML has been updated to version 13, extended support for HTML5 and CSS3, Extended srcset (sizes), a[download] attribute, Canvas ellipse, SVG external content, WebRTC - Object RTC API (desktop).
13.10565 23.10565 October 12, 2015 CSS initial and unset values, initial support for docked F12 Developer Tools.
13.10586 25.10586 November 5, 2015 First public platform update, includes further enhancements to HTML5, including Object RTC support.[6]
13.11099 27.11099 January 13, 2016 Initial foundational work for EdgeHTML 14.
14.14267 31.14267 February 18, 2016 Edge HTML has been updated to version 14, with initial plumbing for Web Notifications support.
14.14279 31.14279 March 4, 2016 New experimental JavaScript feature support.
14.14291 34.14291 March 17, 2016 Preview support for the VP9 video format on some devices.
14.14316 37.14316 April 6, 2016 New F12 Developer Tools, New JavaScript features and experimental features and new Web Platform features.
14.14327 37.14327 April 20, 2016 Beacon interface and accessibility improvements.
14.14342 38.14342 May 10, 2016 Web Notifications, Beacon and Fetch APIs became enabled by default, Performance improvements for several common JavaScript APIs.
14.14352 38.14352 May 26, 2016 H.264/AVC decoding became available through the ORTC API.
14.14356 38.14356 June 1, 2016 Various performance and reliability improvements and bug fixes.
14.14361 38.14361 June 8, 2016 TCP Fast Open is now disabled by default.
14.14366 38.14366 June 14, 2016 Fixed an issue that could result in abnormally high CPU usage when open to a page with many animated GIFs, as well as an issue resulting in certain captchas not displaying correctly.
14.14367 38.14367 June 16, 2016 Improvements to reduce battery usage on Windows 10 Mobile when Microsoft Edge is running in the background.
14.14376 38.14376 June 28, 2016 Bug fixes and performance improvements.
14.14393 38.14393 August 2, 2016 This is the stable channel release of EdgeHTML 14 with the Windows 10 Anniversary Update.
14.14901 39.14901 August 11, 2016 This release adds about:flags settings for several features in development, including support for WebRTC 1.0 and Service Worker features.
14.14915 39.14915 August 31, 2016 Partial implementation of Webkit-Text-Stroke and CSS outline-offset, partial support for WebRTC 1.0.
14.14926 39.14926 September 14, 2016
  • Improved performance on websites with changes to large numbers of HTML Elements containing text by improving spellchecker efficiency. This results in substantially improved performance on websites like TweetDeck.
  • Addressed the largest cause of reliability issues in Insider builds of Microsoft Edge, which should improve reliability on major sites such as Facebook and Outlook.
15.14942 39.14942 October 7, 2016

EdgeHTML has been updated to version 15 with the following features :

  • Enabled H.264/AVC support by default for RTC scenarios
  • Improved ES6 Modules debugging experience in F12 Developer Tools
  • Various webpage performance improvements
  • Refactoring network logic in terms of Fetch algorithms in preparation for Service Worker Fetch interception (behind a flag)
  • Ongoing work to add support for CSS Custom Properties
  • Ongoing work to add support for CSP 2.0, WebRTC 1.0 and Service Worker
15.14959 39.14959 November 3, 2016 Bug fixes and reliability improvements.
15.14986 39.14986 December 7, 2016 Multiple new platform features and developer tools.
15.15063 40.15063 April 11, 2017 This is the stable channel release of EdgeHTML 15 with the Windows 10 Creators Update.
16.16299 41.16299 October 8, 2017 This is the stable channel release of EdgeHTML 16 part of the 2017 Fall Creators Update, having WebAssembly enabled by default.
17.17134 42.17134 April 30, 2018
18.17763 44.17763 November 13, 2018
18.18362 44.18362 May 21, 2019
18.18363 44.18363 November 12, 2019
18.19041 44.19041 May 27, 2020

EdgeHTML 12[edit]

Microsoft first introduced the EdgeHTML rendering engine as part of Internet Explorer 11 in the Windows Technical Preview build 9879 on November 12, 2014.[7] Microsoft planned to use EdgeHTML both in Internet Explorer and Project Spartan; in Internet Explorer it would exist alongside the Trident 7 engine from Internet Explorer 11, the latter being used for compatibility purposes. However, Microsoft decided to ship Internet Explorer 11 in Windows 10 as it was in Windows 8.1,[8] leaving EdgeHTML only for the new Edge browser. EdgeHTML was also added to Windows 10 Mobile and the second Windows Server 2016 Technical Preview. It was officially released on July 29, 2015 as part of Windows 10.[9]

Unlike Trident, EdgeHTML does not support ActiveX. It also drops support for the X-UA-Compatible header, used by Trident to determine in which version it had to render a certain page. Microsoft also dropped the usage of Compatibility View-lists.[10] Edge will recognize if a page requires any of the removed technologies to run properly and suggest to the user to open the page in Internet Explorer instead. Another change was spoofing the user agent string, which claims to be Chrome and Safari, while also mentioning KHTML and Gecko, so that web servers that use user agent sniffing send Edge users the full versions of web pages instead of reduced-functionality pages.

EdgeHTML also made significant performance improvements over Trident, resulting in better JavaScript benchmark scores.[11]

Microsoft EdgeHTML 12 Mozilla/5.0 (Windows NT 10.0;) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/42.0.2311.135 Safari/537.36 Edge/12.10240
Internet Explorer 11 Mozilla/5.0 (Windows NT 10.0; Trident/7.0; rv:11.0) like Gecko

Breaking from Trident, the new EdgeHTML engine will be focused on modern web standards and interoperability, rather than compatibility. The initial release of Edge HTML on Windows 10 included more than 4000 interoperability fixes.[12]

EdgeHTML 13[edit]

On August 18, 2015, Microsoft released the first preview to EdgeHTML platform version 13 as part of Windows 10.0.10525, though it was still labeled as version 12. In subsequent updates, the support for HTML5 and CSS3 was extended to include new elements. Microsoft also included support for Object RTC and enabled ASM.js by default after it was added in version 12. The update's main focus was on improving the support for ECMAScript 6 and also including some features from ECMAScript 7. With that update to Chakra Edge provided to most extensive support for ECMAScript 6 according to the Kangax benchmark with 84% (and 90% with all flags enabled), 13% ahead of Mozilla Firefox 42, the then-current version of Firefox and runner-up.[6]

EdgeHTML 13.10586 was released in multiple versions of Windows. On November 12, 2015, the New Xbox One Experience-update for the Xbox One included EdgeHTML 13.10586, replacing Internet Explorer 10 in the process. It was released to Windows 10 as part of the November Update on the same day. On November 18, 2015, the updated got rolled out to Windows 10 Mobile users in the Insider Preview. Finally, Microsoft rolled out the same update to Windows Server 2016 as part of Technical Preview 4.

EdgeHTML 14[edit]

On December 16, 2015, Microsoft released the first build of Redstone. In January and February 2016, 4 other builds followed, all laying the foundational work for EdgeHTML 14. On February 18, 2016, Microsoft released the first version of EdgeHTML 14 as version 14.14267. This version of the engine contained almost no changes in standards support yet, but contained fundamental work for Web Notifications, WebRTC 1.0, improved ECMAScript and CSS support and also contained a number of new flags. Further, Microsoft announced that it is working on VP9, WOFF 2.0, Web Speech API, WebM, FIDO 2.0, Beacon and many other technologies.

On August 2, 2016, EdgeHTML 14 was released to Windows 10 as part of the 2016 Anniversary Update.[citation needed]

EdgeHTML 15[edit]

On April 11, 2017, EdgeHTML 15 was released to Windows 10 as part of the 2017 Creators Update.[citation needed]

EdgeHTML 16[edit]

On October 8, 2017, EdgeHTML 16 was released to Windows 10 as part of the 2017 Fall Creators Update, having WebAssembly enabled by default.[citation needed]

EdgeHTML 17[edit]

On April 30, 2018, EdgeHTML 17 was released to Windows 10 as part of the 2018 April Update (see version history), with features such as Muting tabs with a click, Automatic filling of forms and credit card details, better reading with annotations, grammar tools, and more.[citation needed]

EdgeHTML 18[edit]

On October 2, 2018, EdgeHTML 18 was released to Windows 10 as part of the 2018 October Update (see version history), with features such as Autoplay Policies, CSS improvements, and improvements to the JavaScript engine, Chakra.[13]

Discontinuation in Edge[edit]

Edge was renamed Edge Legacy, when on January 15 2020, Microsoft released "Microsoft Edge Chromium", which on Windows Update can automatically be installed.[14] Edge Legacy was hidden from the start menu, and attempts to launch Microsoft Edge Legacy/EdgeHTML failed. It is possible to run Edge Legacy and the new Edge browser side by side, but support for Edge Legacy ends on March 9, 2021.[15][16] The Xbox One and Xbox Series X and Series S consoles still use Edge Legacy and EdgeHTML version 18.


A review in 2015 of the engine in the latest Windows 10 build by AnandTech found substantial benchmark improvements over Trident, particularly JavaScript engine performance, which is now up to par with that of Google Chrome.[17] Other benchmarks focusing on the performance of the WebGL API found EdgeHTML to perform much better than Google Chrome and Mozilla Firefox.[18]


EdgeHTML's rendering is meant to be fully compatible with the rendering of the Blink and WebKit layout engines, used by Google Chrome and Safari, respectively. Microsoft has stated that "any Edge-WebKit differences are bugs that we’re interested in fixing."[19]

See also[edit]


  1. ^ a b Belfiore, Joe (2018-12-06), Microsoft Edge: Making the web better through more open source collaboration, Microsoft
  2. ^ Hachamovitch, Dean (2007-12-14), Internet Explorer 8 and Acid2: A Milestone, Microsoft
  3. ^ "Microsoft Edge and Chromium Open Source: Our Intent". Microsoft Edge Team. 6 December 2018. Retrieved 8 December 2018.
  4. ^ Mackie, By Kurt; 12/10/2018. "Microsoft Edge Browser To Get New Rendering Engine but EdgeHTML Continues -- Redmondmag.com". Redmondmag. Retrieved 2021-02-13.CS1 maint: numeric names: authors list (link)
  5. ^ "What's powering Spartan? Internet Explorer, of course". Neowin.
  6. ^ a b "Introducing EdgeHTML 13, our first platform update for Microsoft Edge". Windows Blog. Retrieved 19 November 2015.
  7. ^ "Living on the edge – our next step in helping the web just work". IE Blog. Retrieved 19 November 2015.
  8. ^ "Updates from the "Project Spartan" Developer Workshop". IE Blog. Retrieved 6 December 2015.
  9. ^ "Windows 10 Free Upgrade Available in 190 Countries Today". Windows Blog. Retrieved 19 November 2015.
  10. ^ "A break from the past: the birth of Microsoft's new web rendering engine". IE Blog. Retrieved 19 November 2015.
  11. ^ "Edge is blazing fast". Windows Blog. Retrieved April 20, 2016.
  12. ^ Microsoft Edge Team (17 June 2015). "Building a more interoperable Web with Microsoft Edge". Microsoft Edge Dev Blog. Retrieved 8 May 2016.
  13. ^ QuinnRadich. "What's New in Windows 10 for Developers, Tools & Features - UWP app developer". docs.microsoft.com. Retrieved 2018-11-13.
  14. ^ Joe Belfiore. "What's New in Windows 10 for Developers, Tools & Features - UWP app developer". blogs.windows.com/windowsexperience/. Retrieved 2020-11-30.
  15. ^ https://techcommunity.microsoft.com/t5/discussions/tutorial-how-to-run-legacy-and-chromium-based-edge/m-p/1121216
  16. ^ Fosmark, Tami. "Microsoft 365 apps and services to end support for IE 11; End of support coming to the legacy version of Microsoft Edge". docs.microsoft.com. Retrieved 2021-02-07.
  17. ^ Brett Howse. "AnandTech - Internet Explorer Project Spartan Shows Large Performance Gains". anandtech.com.
  18. ^ "Benchmark Deep-Dive: Microsoft Windows 10 Spartan Browser vs. IE11 vs. Google Chrome 41 vs. Mozilla Firefox". WinBuzzer. Retrieved 9 February 2015.
  19. ^ "Building a more interoperable Web with Microsoft Edge".

Further reading[edit]