Updated 2 months ago by Yvonne

JS.Navigator is a set of Javascript objects that stores various parameters and their values that describe specifics of a computer it executes on. All JS.Navigator object parameters are freely accessible by a browser. Since they possess certain uniqueness, especially when combined, websites may utilize these parameters for user fingerprinting and tracking. 

Websites may also analyze these properties for consistency to reveal cases of fingerprint altering. Such analysis may reveal the usage of browser fingerprint randomizers such as Random Agent Spoofer Firefox add-on.


A User-Agent is a short string native to the browser. By reading a User-Agent string,  a website is able to identify your browser and operating system versions. 

This is an example of a User-Agent value:

Mozilla/5.0 (Windows NT 6.3; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/62.0.2785.8Safari/537.36

In this case, the website will assume that the user is using Windows 7 and Chrome version 62. "NT X"" is the version of a Windows release. You may check other release versions from a Wikipedia article

When creating a browser profile, an User-Agent value will be retrieved from a fingerprint database. An operation system filter from the Overview page will be honored. You may check the User-Agent value of a browser profile on the Navigator page.

If you do decide to configure User-Agent manually in Multilogin, make sure to set a corresponding Platform value. Discrepancies in User-Agent and Platform values are a big red flag. 


The platform property is a Navigator object parameter which tells for which platform the browser was compiled.

When creating a browser profile, a Platform value is retrieved together with an User-agent.  Both values are affected by the Operation System filter from the Overview page.  You may also set this value manually on the Navigator page.

If you do decide to configure Platform manually in Multilogin, make sure to set a corresponding User-Agent value. Discrepancies in User-Agent and Platform values are a big red flag. 

Possible Platform values for desktop browsers:

Linux i686
Linux armv7l

Possible Platform values for mobile browsers:


The full list of possible Navigator.Platform values can be found in a Stackoverflow article.

Screen resolution

Analyzing screen resolution value is a commonly used method of browser fingerprinting.  Websites also may analyze discrepancies between the screen resolution declared by a browser and actually available screen area size. These discrepancies may signal the usage of online privacy tools such as privacy browser add-ons. 

In Multilogin, a screen resolution is retrieved from a fingerprint database upon browser profile creation. You may also change this parameter manually by either selecting the desired resolution from the list of commonly used resolutions or entering one manually. The screen resolution list and resolutions your receive when getting a new fingerprint from the database are both adjusted to the Operation System chosen on the Overview page.

Multilogin will launch a browser maximized to the resolution set in browser profile settings. Having a browser window maximized is a typical behavior for most users and we do not advise reducing its size. We also do not advise using screen resolutions that are bigger than your native screen resolution because websites will see that you are not working in a maximized window. 

When sharing a browser profile to someone else, we recommend that the resolution used in a browser profile should not exceed that of the smallest screen used in your team. E.g. your device is 4K and your colleague uses FullHD (1920x1080) display. In this case, we recommend keeping the resolution in a browser profile to 1920x1080 or smaller. Otherwise, the actual size of a window may be different when a browser profile is opened on different devices. 


Language property of Navigator object helps websites to identify your preferred language. Based on this value websites may adjust the language of content they serve you. As with any other navigator object value, it may be used fingerprint your browser.

When creating a browser profile, the most popular language property is set. Multilogin does not retrieve this value from a fingerprint database since this could lead to a major mismatch between a browser language and IP location. For example, you could end up having Philippine language preference somewhere in Germany. 

Instead, we provide a convenient tool to edit this value. You may both copy-paste Language parameter from your regular browser (e.g. Chrome) or construct it with our builder. 

This mechanism will be further improved in upcoming versions of Multilogin.


DoNotTrack (DNT) is a Navigator object property that returns the user's do-not-track browser setting. It was meant so the user could opt-out from being tracked by settings it to "On". However, most of the websites do not honor this choice. 

Instead, they use it as an additional data point used to increase the precision of user fingerprinting. 

In Multilogin, the default value for DoNotTrack is "Not set" or unspecified which means a user didn't make any proactive choice. This matches the behavior for an absolute majority of internet users. 

While it is possible to change these settings manually, we advise leaving the default value in all browser profiles.


BuildID is a Navigator property, which returns the build identifier of the browser. This value is specific to only Firefox based browsers. Typically, BuildID comes in YYYYMMDDHH format.

Multilogin retrieves BuildID value from a fingerprint database for Stealthfox browser profiles. It is not advised to change this parameter manually.


HardwareConcurency is a Navigator object parameter that indicates the number of CPU processors available to run threads on a user's computer. Values 1, 2, 8, 16, 32, 64 and others are valid. In Multilogin, the range is restricted to the most common values 2, 4, 8, and 16. If a different value is retrieved from a fingerprint database, it will be replaced by one of the commonly found values.

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