Mozilla Firefox 91 brings support for Windows single sign-on

Firefox Logo Horizontal Lockup 4
Firefox Logo Horizontal Lockup 4 (Image credit: Mozilla)

What you need to know

  • Mozilla recently released Firefox version 91.
  • Firefox 91 includes support for Windows single sign-on, making it easier to sign in to Microsoft accounts on the web.
  • The latest version of the browser also has over 1,200 bug fixes and a handful of other new features.

Mozilla released Firefox version 91 this week. The latest version of the browser has over 1,200 bug fixes and a handful of new features compared to its predecessor. Among its new features is support for Windows single sign-on (SSO). This feature lets you log in to Microsoft work and school accounts with credentials from your PC.

The update also adds a "more comprehensive logic for clearing cookies," according to Mozilla. This prevents hidden data leaks.

Here's what's new, as outlined by Mozilla:

  • Building on Total Cookie Protection, we've added a more comprehensive logic for clearing cookies that prevents hidden data leaks and makes it easy for users to understand which websites are storing local information. Learn more
  • Firefox now supports logging into Microsoft, work, and school accounts using Windows single sign-on. Learn more
  • The simplify page when printing feature is back! When printing, under More settings > Format select the Simplified option when available to get a clutter-free page. Learn more
  • HTTPS-First Policy: Firefox Private Browsing windows now attempt to make all connections to websites secure, and fall back to insecure connections only when websites do not support it. Learn more
  • We've added a new locale: Scots (sco)
  • The address bar now provides Switch to Tab results also in Private Browsing windows.
  • Firefox now automatically enables High Contrast Mode when "Increase Contrast" is checked on MacOS
  • Firefox now does catch-up paints for almost all user interactions, enabling a 10-20% improvement in response time to most user interactions.

Firefox 91 performs catch-up paints for "almost all user interactions," according to Mozilla. The company explains that this results in a 10-20% improvement in response time for most interactions.

Sean Endicott
News Writer and apps editor

Sean Endicott brings nearly a decade of experience covering Microsoft and Windows news to Windows Central. He joined our team in 2017 as an app reviewer and now heads up our day-to-day news coverage. If you have a news tip or an app to review, hit him up at