[15] The developer toolset features an option to emulate the rendering behaviour ("document mode") of Internet Explorer versions 5 to 11.

[21] Edge does not support legacy technologies such as ActiveX and Browser Helper Objects, instead it uses an extension system based on the cross-browser WebExtension API.

Every major release of Windows included an updated version of Edge and its render engine.

In December 2014, writing for ZDNet, technology writer Mary Jo Foley reported that Microsoft was developing a new web browser codenamed "Spartan".

[26] In early January 2015, The Verge obtained further details surrounding "Spartan" from sources close to Microsoft, including reports that it would replace Internet Explorer on both the desktop and mobile versions of Windows.

[28] "Spartan" was first made publicly available as the default browser of Windows 10 Technical Preview build 10049, released on March 30, 2015.

[41] The rendering engine was first released as an experimental option in Internet Explorer 11 as part of the Windows 10 Preview 9926 build.

[45] Early benchmarks of the EdgeHTML engine—included in the first beta release of Edge in Windows 10[60] Build 10049—had drastically better JavaScript performance due to the new Chakra than MSHTML (Trident) 7 using the older Chakra in Internet Explorer 11, with similar performance to Google Chrome 41 and Mozilla Firefox 37.

[62] Later benchmarks conducted with the version included in 10122 showed significant performance improvement compared to both IE11 and Edge back in 10049.

[66] In July 2016, with the release of Windows 10 Build 14390 to insiders, the HTML5 test score of the browser's development version was 460 out of 555 points.

[68] In June 2016, Microsoft published benchmark results to prove the superior power efficiency of Edge in comparison to all other major web browsers.

[71] However, tests conducted by Linus Sebastian in June 2017 instead showed that, at that time, Chrome had the best battery performance.

[72] In an August 2015 review of Windows 10 by Dan Grabham of TechRadar, Microsoft Edge was praised for its performance, despite not being in a feature-complete state at launch.

[74] Thom Holwerda of OSNews criticized Edge in August 2015 for its hidden URL bar, lack of user friendliness, poor design and a tab system that is "so utterly broken it should never have shipped in a final release".

[76] In October 2015, a security researcher published a report outlining a bug in Edge's "InPrivate" mode, causing data related to visited sites to still be cached in the user's profile directory, theoretically making it possible for others to determine sites visited.

[78] According to StatCounter, in August 2019, Edge overtook the market share of Internet Explorer (IE) on PCs, ranking third place at 9.14%[79] and IE in sixth.