User Agent

A User Agent (UA) is a specific string automatically sent by the browser to the server upon each HTTP request. It contains information about the user's device, operating system, browser version, and, in some cases, the interface language. For example, a UA may appear as follows:

Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/138.0.0.0 Safari/537.36

By analyzing this string, the system can determine which device the user is using, which content version to display (mobile or desktop), and what adaptive logic to include in client scripts.

User Agent in cloaking schemes

In cloaking, the User Agent is one of the main parameters for filtering traffic. It can be used to recognize who is visiting the page: a real user or a bot moderator.

For example, User Agents such as HeadlessChrome or FacebookExternalHit often indicate scanners and automatic verification systems. When detected, the cloaking system loads a "white" version of the page, minimizing the risk of blocking. UA also allows adjusting content instantly to match the device type.

How to determine the user's platform and browser via User Agent?

User Agent is capable of determining platform signatures and identifying the browser based on keys. It is possible to redirect Android or iPhone users to the target offers instantly. Additionally, some anti-bot systems utilize UA as part of a set of behavioral signatures to detect suspicious activity. It can look like this: Edge → Edg/114.0.0.0, Chrome → Chrome/114.0.0.0, macOS → Macintosh.

UA can be swapped, as this is one of the weak spots, especially in anti-fraud. That is why it is often used in combination with other parameters for more accurate filtering (IP, screen resolution, cookies, behavioral patterns).

Why change the User Agent and how to do it?

The User Agent can be easily replaced either manually or with the help of special tools. It is an essential part of arbitration cloaking. Swapping is used when farming accounts and working with anti-detection browsers (to avoid repeated digital fingerprints) or when testing to emulate the behavior of different devices. Another goal may be to bypass filters and obtain alternative versions of the site that are not available with the usual configuration.

The UA can be changed via the browser interface. For example, one can use DevTools in the Network conditions section, using extensions such as User-Agent Switcher. In anti-detection environments, Dolphin{anty}, AdsPower, or Incogniton will do the trick. Another option is the HTTP request during parsing and automation.

In arbitrage, User Agent becomes part of a comprehensive strategy to obfuscate behavior, as it affects the "purity" of accounts, moderation approval, cloaking accuracy, and overall advertising funnel effectiveness.