Mozilla Firefox ESR is a free web browser for Windows, macOS and Linux, intended for organizations that need to run websites and web applications with a predictable pace of browser changes. ESR stands for Extended Support Release. It combines Firefox’s browsing tools with a release cycle that gives administrators longer intervals between major feature changes.
The Firefox ESR release cycle
Mozilla Firefox ESR receives major releases annually, with security fixes delivered through smaller updates in between. Interface and usability changes are reserved for the major ESR releases.
That schedule matters when an organization checks its internal applications against a browser before rolling changes out to staff. ESR reduces the frequency of major changes that need that testing. The regular Firefox release channel receives new features more frequently, so it suits deployments that want those additions sooner.
Browser policies
Administrators can configure Mozilla Firefox ESR through Windows Group Policy, Intune or a cross-platform policies.json file. Firefox reads the settings and applies them to the browser, allowing an organization to distribute its chosen configuration through existing management tools. The about:policies page shows which policies have been applied.
Policies control concrete browsing behavior. An organization can set an intranet homepage and lock it against changes, provide managed bookmarks that users cannot alter, or require downloads to use a particular folder. These controls let staff receive the same starting pages and shared links without setting them up individually.
Firefox ESR is free, while Firefox Professional Support is an optional paid service. Firefox Enterprise is a separate paid platform with centralized browser governance; its management console is separate from the policy controls available in ESR.
Extension rules
Extensions add functions to Firefox, and ESR lets administrators determine which ones reach managed computers. The ExtensionSettings policy identifies each extension by its ID and assigns an installation rule. It can allow a user to install an extension, block it, or install it automatically.
An administrator can block extensions by default and create exceptions for approved ones. A forced installation prevents users from removing the required extension; another installation mode allows users to disable it. Blocking an extension also removes it if it is already installed, so the rule covers existing installations as well as future requests.
Address bar and bookmarks
Firefox ESR uses a combined address and search bar for opening known web addresses and finding information. As a user types, it can suggest matches from browsing history, bookmarks and open tabs.
Bookmarks save a page’s address under a chosen name and location. Users can keep frequently used pages on the Bookmarks Toolbar or place them in the menu for later access. Those personal bookmarks sit alongside any managed links supplied by an organization.
Tracking controls
Enhanced Tracking Protection blocks categories of known trackers, including cross-site tracking cookies, social-media trackers, fingerprinters and cryptominers. Its Standard setting also separates cookies by website, limiting their use across different sites. Strict mode extends tracking-content blocking from private windows to ordinary browsing windows; Custom mode lets users choose the categories to block.
The shield beside the address bar exposes information about blocked content and controls protection for the current site. Stronger blocking can affect embedded videos, forms or sign-in components that depend on outside content. A site-specific exception allows that content to load while retaining the selected protection on other websites.
