The Edge browser may have a small market share, but research commissioned by Firefox shows how Microsoft muscles in
A report co-authored by an expert in deceptive user interfaces and a technology and design ethicist has found that design choices in the Edge browser and Windows influence browser choice.
The Over the Edge 2.0 report, commissioned by Mozilla, found that Microsoft is failing to honour Windows users’ wishes when they select an alternative to Edge as their default web browser.
The report’s authors, Harry Brignull, author of Deceptive patterns, and technology and design ethicist Cennydd Bowles, reported that Microsoft still does not allow users to download, set as the default or keep using alternative browsers without harmful interference.
Citing data from StatCounter, the report shows that in the UK, while Chrome remains the most popular web browser, it has experienced an almost 5% (4.99%) drop in browser share on Windows computers when comparing data from the first quarter of 2024 and the first quarter of 2026. For the same period, Firefox saw a drop in share of almost 1.5%. However, during the same period, Microsoft Edge grew its share in the UK by 6.7%.
Globally, this means that while Chrome is the most used web browser, representing 73% of Windows users, Edge now has a 12.4% share, while Firefox is the third most popular Windows web browser, with 9.3% share.
The report’s authors documented installing Windows from scratch in various geographic regions to check if Microsoft allows users to switch default browsers. Their analysis shows that when the Microsoft Bing internet search engine is used to download a rival browser, the Bing result sometimes presents a panel at the top of the search list, highlighting Microsoft Edge. “The intention of this panel is clear: to dissuade a user from downloading the rival browser,” they said.
The report states: “Microsoft is within its rights to run promoted adverts against competitor keywords; this functionality is offered by most major search engines. But this banner is not a standard ad unit. It is larger and more eye-catching, and employs a unique comparison table to target a rival. We have no evidence that Microsoft offers this form of ad unit to other companies, and therefore conclude this is a custom content injection that uses harmful patterns to skew browser choice in Microsoft’s favour. We did not observe these harmful patterns being used in either Windows 10 or 11 when the OS region was set to the EEA.”
When the authors attempted to download Chrome from the download page on Google.com, they said they encountered a screen with a large banner proclaiming that “Microsoft Edge runs on the same technology as Chrome”.
An identical banner was observed when a Windows 10 PC was used (in the US, India and UK) and a Windows 11 PC (in the US, India and UK).
Commenting on the advert on the Google.com Chrome browser download page, the report’s authors said: “We find that its design uses the ‘visual interference’, ‘disguised ads’ and ‘trick wording’ harmful patterns.”
They stated that by embedding the advert promoting the Edge browser at the top of the browser page to download Chrome, Microsoft “violates a browser’s expected duties in severe, unprecedented ways. The banner is not of Google’s making. Instead, Edge is injecting content directly into the rendering of a competitor’s website.”
Brignull and Bowles note that browser developers usually only intervene in the normal rendering of a web page when a website’s security certificate is out of date or a secure connection cannot be established to the web server hosting the page.
Microsoft has previously used its dominance as the provider of PC operation systems to preinstall its web browser and other apps on Windows PCs. This practice has led to several investigations by regulators including the 1998 US Department of Justice (DoJ) anti-trust case.
To comply with the EU Digital Markets Act (DMA), in 2024, Microsoft announced that its Edge browser and the Bing web search functionality had been redesigned so that users can uninstall these applications from Windows using the standard Windows uninstall mechanism. Microsoft said it also gives third-party web search applications the ability to offer web search services through the search box on the Windows task bar and to rely on any browser of their choice.
Brignull and Bowles conclude that outside of the EEA, Microsoft does not enable Windows users to download, install and set alternative browsers as their default without “harmful intervention”.
They point out that while its market share is relatively low compared with Chrome, Edge is intricately linked to Windows, which is the dominant operating system on PC hardware. They urge other regulators to take similar action as the EEA has done with the DMA, to improve Windows browser choice.
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