Firefox 155 shows blocked trackers

Firefox 155 now displays a number in the address bar that was previously hidden behind the shield icon and privacy reports: how many trackers—that is, elements that can track users across websites—the browser has blocked. Mozilla has released the new version, making an existing protection feature visible without changing its default behavior.

In everyday use, this provides more control at a glance. Users who do not want to see the display can disable it in the settings; tracking protection remains active. Containers are also easier to organize: Their order can now be set. Because they keep cookies, logins and website data separate, users can run multiple accounts for the same service in parallel without needing different Firefox profiles or browser windows.

Mozilla is also expanding the gradual beta test of Smart Window to France. The AI feature requires Firefox for desktop and a Mozilla account, bundles several functions and is expected to need around one fifth of the previous response time for web searches. The assistant is supposed to cite sources from Exa directly. Mozilla has not announced a launch in Germany, Austria or Switzerland.

The most important caveat concerns corporate networks. If firewalls or proxies block UDP—a network protocol for fast, connectionless transmission—for example during TLS inspection, websites may load slowly or fail. Firefox 155 also supports QUIC Version 2 for HTTP/3; administrators can temporarily bypass the problematic connection strategy using a policy. According to Mozilla, a permanent fix is being developed for a subsequent minor version.

So, what does this mean in practice? Private users can see more quickly what Firefox is already blocking and organize containers more effectively. Web gamers on Windows also get full support for Nintendo Switch Pro controllers. In companies, however, the update may initially create extra checking work: Allowlists must be adjusted for the new portal detection domain, and the UDP setting may remain relevant until the next minor-version update.