When you open Apple's Business website in Mozilla Firefox, you are greeted by a "your browser is not supported" prompt. The message is displayed for all recent versions of Firefox, including Firefox Stable, Firefox ESR and Firefox Nightly.
Apple states that it recommends Safari, Microsoft Edge or Chrome to access the Business site, but most Chromium-based browsers work. The business login is displayed when you open the site in Brave or Opera, and of course the three mentioned web browsers that Apple recommends.
Apple does not reveal why Firefox is not supported. Is it a technical limitation that is preventing Firefox from being supported by Apple's Business site? While possible, there is also the possibility that Apple blocks any browser that is not Webkit (its own) or Chromium-based.
Some organizations recommend certain web browsers. Besides Microsoft and Google, which push their browsers on their properties heavily, it is organizations such as Bank of America and other financial institutions that recommend certain web browsers. Sometimes, these recommendations are based on tests or the lack thereof.
If companies have a limited test budget, they will spend it on widely used browsers and applications first. Most of the time, non-recommended browsers may be used, provided that they support the technologies that the sites use.
Firefox users may skip the blocking of their web browser on Apple's Business site by changing the user agent of the browser. The user agent is often used as an identifier, as it may reveal the name and version of the browser, as well as other information.
When you change the Firefox user agent to that of Chrome, Apple's Business site loads the login prompt, asking to sign-in to the site.
