4 methods to find, copy, and override your Firefox user agent on desktop, Android, and Linux
The quickest way is to open the Web Console with Ctrl+Shift+K (Cmd+Option+K on Mac), type navigator.userAgent, and press Enter. You can also type about:support in the address bar and find the User Agent row in the Application Basics section.
Firefox's Web Console gives you instant access to your user agent string. Unlike Chrome's DevTools, Firefox has a dedicated keyboard shortcut just for the Console.
Press Ctrl+Shift+K (Mac: Cmd+Option+K ) to open the Web Console directly
Firefox has a built-in troubleshooting page that shows your full user agent alongside detailed browser information — no developer tools required.
Find the "User Agent" row in the Application Basics table
This page also shows your Firefox version, profile folder, installed extensions, crash reports, and graphics driver information — useful for troubleshooting.
Unlike Chrome's temporary UA override, Firefox lets you permanently change your user agent string via about:config. This persists across sessions and tabs.
If it doesn't exist, click + to create it as a String
The easiest method — works on desktop and mobile Firefox without any setup:
Firefox's user agent is more straightforward than Chrome's. Here's how each component maps:
Firefox on Android is one of the few mobile browsers that uses its own engine (GeckoView) instead of the system WebView. This means its user agent is genuinely different from Chrome on Android.
Note: Firefox for iOS (FxiOS) uses WebKit, not Gecko, due to Apple's App Store requirements. Its UA string is completely different from desktop/Android Firefox.
The quickest way is to open the Web Console with Ctrl+Shift+K (Cmd+Option+K on Mac), type navigator.userAgent, and press Enter. You can also type about:support in the address bar and find the User Agent row in the Application Basics section.
A typical Firefox UA string is: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:133.0) Gecko/20100101 Firefox/133.0. Unlike Chrome, Firefox uses 'Gecko' as its engine token and includes the 'rv:' (release version) token inside the platform section.
Yes. Type about:config in the address bar, accept the warning, search for 'general.useragent.override', create the preference as a string if it doesn't exist, and enter your custom UA string. Unlike Chrome, this persists across sessions until you delete the preference.
No. As of 2026, Firefox does not support the User-Agent Client Hints API (navigator.userAgentData). Mozilla has concerns about the privacy implications and the centralization of the specification around Chromium. For Firefox, you must use the traditional navigator.userAgent string.
Firefox uses 'Gecko/20100101' as its engine token (Chrome uses 'AppleWebKit/537.36'). Firefox includes 'rv:VERSION' in the platform section. Firefox does not include the 'Safari/' compatibility token that Chrome does. Firefox's UA is generally shorter and more straightforward.
On Firefox for Android, you can type about:support in the address bar to see your User Agent in the Application Basics table. Alternatively, visit an online tool like SnapWhatIsMy.com. For developers, you can use remote debugging via USB from desktop Firefox.
The 'rv:' (release version) token shows the Gecko engine version, which matches the Firefox version number. For example, 'rv:133.0' means Gecko 133.0, which corresponds to Firefox 133. This token is unique to Firefox-based browsers and is used by some detection scripts.