# Firefox user agent string reference This document describes the user agent string used in Firefox 4 and later and applications based on Gecko 2.0 and later. For a breakdown of changes to the string in Gecko 2.0, see [Final User Agent string for Firefox 4](https://hacks.mozilla.org/2010/09/final-user-agent-string-for-firefox-4/) (blog post). See also this document on [user agent sniffing](/en-US/docs/Web/HTTP/Guides/Browser_detection_using_the_user_agent) and this [Hacks blog post](https://hacks.mozilla.org/2013/09/user-agent-detection-history-and-checklist/). ## General form The UA string of Firefox itself is broken down into four components: `Mozilla/5.0 (platform; rv:gecko-version) Gecko/gecko-trail Firefox/firefox-version` - `Mozilla/5.0` is the general token that says the browser is Mozilla compatible, and is common to almost every browser today. - `platform` describes the native platform the browser is running on (e.g., Windows, Mac, Linux or Android), and whether or not it's a mobile phone. Firefox OS phones say `Mobile`; the web is the platform. Note that `platform` can consist of multiple `;`-separated tokens. See below for further details and examples. - `rv:gecko-version` indicates the release version of Gecko (such as `17.0`). - `Gecko/gecko-trail` indicates that the browser is based on Gecko. - On Desktop, `gecko-trail` is the fixed string `20100101`. - `Firefox/firefox-version` indicates the browser is Firefox, and provides the version (such as `17.0`). - From Firefox 10 on mobile, `gecko-trail` is the same as `firefox-version`. > [!NOTE] > The recommended way of sniffing for Gecko-based browsers (if you _have to_ sniff for the browser engine instead of using feature detection) is by the presence of the `Gecko` and `rv:` strings, since some other browsers include a `like Gecko` token. For other products based on Gecko, the string can take one of two forms, where the tokens have the same meaning except those noted below: `Mozilla/5.0 (platform; rv:gecko-version) Gecko/gecko-trail app-name/app-version` `Mozilla/5.0 (platform; rv:gecko-version) Gecko/gecko-trail Firefox/firefox-version app-name/app-version` - `app-name/app-version` indicates the application name and version. For instance, this could be `Camino/2.1.1`, or `SeaMonkey/2.7.1`. - `Firefox/firefox-version` is an optional compatibility token that some Gecko-based browsers may choose to incorporate, to achieve maximum compatibility with websites that expect Firefox. `firefox-version` will generally represent the equivalent Firefox release corresponding to the given Gecko version. Some Gecko-based browsers may not opt into using this token; for this reason, sniffers should be looking for Gecko — not Firefox! ## Mobile and Tablet indicators The `platform` part of the UA string indicates if Firefox is running on a phone-sized or tablet device. When Firefox runs on a device that has the phone form factor, there is a `Mobile;` token in the `platform` part of the UA string. When Firefox runs on a tablet device, there is a `Tablet;` token in the `platform` part of the UA string instead. For example: ```plain Mozilla/5.0 (Android 4.4; Mobile; rv:41.0) Gecko/41.0 Firefox/41.0 Mozilla/5.0 (Android 4.4; Tablet; rv:41.0) Gecko/41.0 Firefox/41.0 ``` > [!NOTE] > The version numbers are not relevant. Avoid inferring materials based on these. The preferred way to target content to a device form factor is to use CSS Media Queries. However, if you use UA sniffing to target content to a device form factor, please look for **Mobi** (to include Opera Mobile, which uses "Mobi") for the phone form factor and do **not** assume any correlation between "Android" and the device form factor. This way, your code will work if/when Firefox ships on other phone/tablet operating systems or Android is used for laptops. Also, please use touch detection to find touch devices rather than looking for "Mobi" or "Tablet", since there may be touch devices which are not tablets. > [!NOTE] > Firefox OS devices identify themselves without any operating system indication; for example: "Mozilla/5.0 (Mobile; rv:15.0) Gecko/15.0 Firefox/15.0". The web is the platform. ## Windows Windows user agents have the following variations, where _x.y_ is the Windows NT version (for instance, Windows NT 6.1). | Windows version | Gecko user agent string | | --------------------- | --------------------------------------------------------------------------------- | | Windows NT on x86 CPU | Mozilla/5.0 (Windows NT _x_._y_; rv:10.0) Gecko/20100101 Firefox/10.0 | | Windows NT on x64 CPU | Mozilla/5.0 (Windows NT _x_._y_; Win64; x64; rv:10.0) Gecko/20100101 Firefox/10.0 | > [!NOTE] > An aarch64 CPU is reported as x86_64 on Windows 11, and x86 on Windows 10 (since it doesn't support x64 emulation). > See [Bugzilla #1763310](https://bugzil.la/1763310). ## macOS Here, _x.y_ is the version of macOS (for instance, macOS 10.15). Starting in Firefox 87, Firefox caps the reported macOS version number to 10.15, so macOS 11.0 Big Sur and later will be reported as "10.15" in the User-Agent string. ARM-based Macs will be reported as "Intel" in the User-Agent string. | Mac OS X version | Gecko user agent string | | ----------------------------------- | ---------------------------------------------------------------------------------- | | Mac OS X on x86, x86_64, or aarch64 | Mozilla/5.0 (Macintosh; Intel Mac OS X _x.y_; rv:10.0) Gecko/20100101 Firefox/10.0 | | Mac OS X on PowerPC | Mozilla/5.0 (Macintosh; PPC Mac OS X _x.y_; rv:10.0) Gecko/20100101 Firefox/10.0 | ## Linux Linux is a more diverse platform. Your distribution of Linux might include an extension that changes your user-agent. A few common examples are given below. | Linux version | Gecko user agent string | | --------------------------- | -------------------------------------------------------------------- | | Linux desktop on i686 CPU | Mozilla/5.0 (X11; Linux i686; rv:10.0) Gecko/20100101 Firefox/10.0 | | Linux desktop on x86_64 CPU | Mozilla/5.0 (X11; Linux x86_64; rv:10.0) Gecko/20100101 Firefox/10.0 | > [!NOTE] > In Firefox 127.0 and later, 32-bit x86 will now be reported as x86_64 in Firefox's User-Agent string, {{domxref("navigator.platform")}}, and {{domxref("navigator.oscpu")}} (see [Firefox 127.0 Release Notes](https://www.firefox.com/en-US/firefox/127.0/releasenotes/)). ## Firefox for Android Firefox for Android contains the Android version as part of the _platform_ token. For increased interoperability, if the browser is running on a version below 4 it will report 4.4. Android versions 4 and above report the version accurately. Note that the same Gecko—with the same capabilities—is shipped to all versions of Android. | Form factor | Gecko user agent string | | ----------- | ------------------------------------------------------------------ | | Phone | Mozilla/5.0 (Android 4.4; Mobile; rv:41.0) Gecko/41.0 Firefox/41.0 | | Tablet | Mozilla/5.0 (Android 4.4; Tablet; rv:41.0) Gecko/41.0 Firefox/41.0 | ## Focus for Android From version 1, Focus is powered by Android WebView and uses the following user agent string format: ```plain Mozilla/5.0 (Linux; ) AppleWebKit/ (KHTML, like Gecko) Version/4.0 Focus/ Chrome/ Mobile Safari/ ``` Tablet versions on WebView mirror mobile, but do not contain a `Mobile` token. Starting in Version 6, users can opt into using a GeckoView-based Focus for Android with a hidden preference: it uses a GeckoView UA string to advertise Gecko compatibility. | Focus Version (Rendering Engine) | User Agent string | | -------------------------------- | -------------------------------------------------------------------------------------------------------------------------------------- | | 1.0 (WebView Mobile) | Mozilla/5.0 (Linux; Android 7.0) AppleWebKit/537.36 (KHTML, like Gecko) Version/4.0 Focus/1.0 Chrome/59.0.3029.83 Mobile Safari/537.36 | | 1.0 (WebView Tablet) | Mozilla/5.0 (Linux; Android 7.0) AppleWebKit/537.36 (KHTML, like Gecko) Version/4.0 Focus/1.0 Chrome/59.0.3029.83 Safari/537.36 | | 6.0 (GeckoView) | Mozilla/5.0 (Android 7.0; Mobile; rv:62.0) Gecko/62.0 Firefox/62.0 | The Klar user agent is the same as [Focus](#focus_for_ios). ## Firefox for iOS Firefox for iOS uses the default Mobile Safari UA string, with an additional **FxiOS/\** token on iPod and iPhone, similar to how [Chrome for iOS identifies itself](https://chromium.googlesource.com/chromium/src/+/HEAD/docs/ios/user_agent.md). | Form factor | Firefox for iOS user agent string | | ----------- | ------------------------------------------------------------------------------------------------------------------------------------------- | | iPod | Mozilla/5.0 (iPod touch; CPU iPhone OS 8_3 like Mac OS X) AppleWebKit/600.1.4 (KHTML, like Gecko) **FxiOS/1.0** Mobile/12F69 Safari/600.1.4 | | iPhone | Mozilla/5.0 (iPhone; CPU iPhone OS 8_3 like Mac OS X) AppleWebKit/600.1.4 (KHTML, like Gecko) **FxiOS/1.0** Mobile/12F69 Safari/600.1.4 | | iPad | Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_4) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/13.1 Safari/605.1.15 | On iPad, the user agent string appears identically as Safari. For various issues related to the non-inclusion of `FxiOS` on iOS, see [mozilla-mobile/firefox-ios#6620](https://github.com/mozilla-mobile/firefox-ios/issues/6620). ## Focus for iOS Version 7 of Focus for iOS uses a user agent string with the following format: ```plain Mozilla/5.0 (iPhone; CPU iPhone OS 12_1 like Mac OS X) AppleWebKit/605.1.15 (KHTML, like Gecko) FxiOS/7.0.4 Mobile/16B91 Safari/605.1.15 ``` Note: this user agent was retrieved from an iPhone XR simulator and may be different on device. ## See also - Recommendations on [sniffing the UA string for cross-browser support](/en-US/docs/Web/HTTP/Guides/Browser_detection_using_the_user_agent) - [`navigator.userAgent`](/en-US/docs/Web/API/Window/navigator)