Modern versions of Firefox (currently reaching version 149 in 2026) are strictly incompatible with Windows XP. The Official "Newest" Version for XP
Windows XP’s old antivirus might flag the new browser as a false positive (because it modifies system areas to run on XP). Temporarily disable real-time protection during installation, then re-enable it. Or use VirusTotal to verify the file. Download Mozilla Firefox For Windows Xp Free New Version
Because Mozilla hides old versions on their main site, you must visit their archive. Modern versions of Firefox (currently reaching version 149
If you are searching for you have likely realized that modern web browsing on a 20-year-old operating system is a significant challenge. Microsoft officially ended support for Windows XP in 2014, and major software developers followed suit. Or use VirusTotal to verify the file
Follow these instructions carefully. We assume you are running (32-bit).
Run the .exe file and follow the standard "Next" prompts.
You now have a “new version” of Firefox running on Windows XP. The interface looks like modern Firefox (Quantum), and it supports extensions!