What Does Your User Agent Say About You?


A user agent is a computer program representing a person, for example, a browser in a Web context.

Besides a browser, a user agent could be a bot scraping webpages, a download manager, or another app accessing the Web. Along with each request they make to the server, browsers include a self-identifying User-Agent HTTP header called a user agent (UA) string. This string often identifies the browser, its version number, and its host operating system.

Spam bots, download managers, and some browsers often send a fake UA string to announce themselves as a different client. This is known as user agent spoofing.

The user agent string can be accessed with JavaScript on the client side using the navigator.userAgent property.

A typical user agent string looks like this: "Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:35.0) Gecko/20100101 Firefox/35.0".


User Agent String

Browser Data

Example User Agent String

Maria Johnson
• Sunday, 22 May, 2022
• 10 min read

Platform identifiers change based on the operating system being used, and version numbers also increment as time passes. Mapping UA string tokens to a more human-readable browser name for use in code is a common pattern on the web today.

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When mapping the new Edge token to a browser name, Microsoft recommends using a different name than the one developer used for the legacy version of Microsoft Edge to avoid accidentally applying any legacy workarounds that are not applicable to Chromium-based browsers. When Microsoft is notified about these types of issues, website owners are contacted and informed about the updated UA.

Rv: gecko version indicates the release version of Gecko (such as 17.0 “). For compatibility, it adds strings like HTML, like Gecko and Safari.

The Opera browser is also based on the Blink engine, which is why it almost looks the same, but adds “Or/”. In this example, the useragentstring is mobile Safari’s version.

The landscape of mobile browsers is quite complex, with several major players (pre-installed in most cases) and a number of locally popular contenders. While all phones come with pre-installed browsers, both Google Play and Apple App Store offer a number of alternative browsers, some focusing on speed and lightness, others on saving bandwidth and blocking ads, and an ever-increasing amount claiming to increase privacy and reduce a users' mobile digital footprint.

A simple regex solution searching for keywords will struggle in terms of accuracy and detection speed. It offers a patented algorithm that detects and identifies all devices requesting online content through parsing UA strings based on a constantly updated, massive list of connected devices.

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Mozilla/5.0 : Previously used to indicate compatibility with the Mozilla rendering engine. (HTML, like Gecko) : Browser platform details.

Automated agents are expected to follow rules in a special file called robots.txt “. The popularity of various Web browser products has varied throughout the Web's history, and this has influenced the design of websites in such a way that websites are sometimes designed to work well only with particular browsers, rather than according to uniform standards by the World Wide Web Consortium (W3C) or the Internet Engineering Task Force (IETF).

Websites often include code to detect browser version to adjust the page design sent according to the useragentstring received. Thus, various browsers have a feature to cloak or spoof their identification to force certain server-side content.

For example, the Android browser identifies itself as Safari (among other things) in order to aid compatibility. User agent sniffing is the practice of websites showing different or adjusted content when viewed with certain user agents.

An example of this is Microsoft Exchange Server 2003's Outlook Web Access feature. When viewed with Internet Explorer 6 or newer, more functionality is displayed compared to the same page in any other browsers.

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Web browsers created in the United States, such as Netscape Navigator and Internet Explorer, previously used the letters U, I, and N to specify the encryption strength in the useragentstring. Until 1996, when the United States government disallowed encryption with keys longer than 40 bits to be exported, vendors shipped various browser versions with different encryption strengths.

^ a b RFC 3261, SIP: Session Initiation Protocol, IETF, The Internet Society (2002) ^ RFC 7231, Hypertext Transfer Protocol (HTTP/1.1): Semantics and Content, IETF, The Internet Society (June 2014) ^ Net news Article Format. Browser Versions Carry 10.5 Bits of Identifying Information on Average “, Electronic Frontier Foundation, 27 January 2010.

^ User Agent String explained: Android WebKit Browser”. Mozilla/5.0 (Linux; U; Android 2.2; ends; HTC_DesireHD_A9191 Build/FRF91) Apple WebKit/533.1 (HTML, like Gecko) Version/4.0 Mobile Safari/533.1 ^ Emberton, Stephen.

An user agent is a string that a browser or application sends to each website you visit. Web servers use this data to assess the capabilities of your computer, optimizing a page’s performance and display.

Ignore the X-Amzn-Trace-Id as it is not sent by Python Requests, instead generated by Amazon Load Balancer used by Hatpin. Any website could tell that this came from Python Requests, and may already have measures in place to block such user agents.

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In order to make your requests from web scrapers look as if they came from a real browser: They have a huge database of the combination of headers that are sent by specific versions of a browser on different operating systems and websites.

Have a Referee header with the previous page you visited or Google, to make it look real There is no point rotating the headers if you are logging in to a website or keeping session cookies as the site can tell it is you without even looking at headers We advise you to use proxy servers when making many requests and use a different IP for each browser or the other way Rotating user agents can help you from getting blocked by websites that use intermediate levels of bot detection, but advanced anti-scraping services has a large array of tools and data at their disposal and can see past your user agents and IP address.

We are not responsible for how it is used and assume no liability for any detrimental usage of the source code. The tutorials only help illustrate the technique of programming web scrapers for popular internet websites.

We are not obligated to provide any support for the code, however, if you add your questions in the comments section, we may periodically address them. Sergeant strings come in all shapes and sizes, and the number of unique user agents is growing all the time.

If you need to integrate the user agent parser directly into your website or system then it's very simple to use the API. This will let you do things like advanced filtering and searching, identify trends in user agents, perform statistical analysis and other interesting applications.

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It is possible to change or “fake” what your web browser sends as its user agent. Some mobile web browsers will let you change what the browser identifies itself as (i.e. “Mobile Mode” or “Desktop Mode”) in order to access certain websites that only allow desktop computers.

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