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.
A typical user agent string looks like this: "Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:35.0) Gecko/20100101 Firefox/35.0".
From a web developer’s perspective, User-Agent strings can be useful when it comes to testing how online content is rendered on various hardware and software combinations. 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. Feel free to browse the stats for your local market using our Data Explorer tool.
A simple regex solution searching for keywords will struggle in terms of accuracy and detection speed. To tackle these issues you may want to consider using a specialized device detection provider, such as Device Atlas.
The User-Agent (UA) string is contained in the HTTP headers and is intended to identify devices requesting online content. The User-Agent tells the server what the visiting device is (among many other things) and this information can be used to determine what content to return.
Of course this requires using a device detection solution which translates UAS into understandable software and hardware information. If you’d like to learn more on these devices, just copy and paste the UAS to our User-Agent testing tool.
Optimize website content for mobile, tablet, and other devices Boost website loading time and minimize page weight Handle traffic from any device as you want First tip : If you only need a very simple and minimal solution to detect brand and model, go with WU RFL if you want it for free or Device Atlas if you can afford it.
Second tip : As a general rule, it is a good idea to stay tuned with the W3C standards. It describes an abstract API to access Device Description Repositories (DDR).
You can find an open-source reference implementation of that API in Java as part of MyMobileWeb project (dead link). What that means, in practice, is that you can develop your application using WU RFL and later switch to another repository, keeping your code ideally untouched.
I have to say I've previously worked on that project, I think it's worth a look in any case, despite W3C standards are usually hard to read. Let's talk about how the Accept-CH and Sec-CH-UA-* headers will work, how you can test that with your own services today, and what comes next.
You might be serving content that depends on the specific browser version a user is using (either because the content itself is relevant to the browser, or because you need to work around behavior in specific known versions), or you might be serving content that depends on the user's specific OS and OS version (offering a Mac download to Mac users and a Windows download to Windows users). These cases exist, and will continue to be supported, but explicitly: the server will need to send an Accept-CH header to request this information.
It's been supported in Chrome on desktop & Android since 2015, and other Chromium-based browsers, though it's not yet available in Firefox or Safari. Until now, it's been used to request bonus details from browsers, such as the user's connection speed, viewport size or screen density.
The exact lifetime is left up to the client (a previous draft included an Accept-CH-Lifetime header, but that's now been removed) but it's likely to be at least the rest of the current browser session. All of this is Chrome only right now, although there's some progress in other browsers, and the standardization process is intended to encourage that.
The set of opt-in hints supported in the latest stable Chrome includes: This is a general prefix for a forbidden header name as defined by the Fetch spec.
Right now, the only browser that supports this is Chrome, and only in the dev & canary channels, and behind a flag. That said, testing it out now allows you to see how this might impact your application, and start to see how you can capture any hints that you need to handle this, once this does land for real.
Safari haven't formally announced their position, but they've previously attempted to freeze the UA in preview builds (though that was partially rolled back), and it seems likely they'd follow suit once the rest of the ecosystem commits to this. Watch out for more changes in the same direction too, as browsers move other finger printable data behind client hints in the future, including the Accept-Language header, and begin investigating approaches like GREASE to mitigate sniffing risks.
You can follow the detailed progress on this in the Chromium and Firefox bug trackers. Accept-CH in general is now in its last call for comments, until the 8th of May 2020, whilst the UA freezing and client hints details are still very much subject to change, with discussion happening in the Wing ua-client-hints repo on GitHub.
Editor's note: user agent detection is not a recommended technique for modern web apps. It is suggested to use one of the other answers using feature detection and/or media queries.
So I use CSS Media Queries do show/hide elements depending on the screen size. For example, in my mobile version I don't want to activate the Facebook Like Box, because it loads all those profile images and stuff.
So, besides hiding the container element, I also do this inside the jQuery code block (above): The advantage of this method is that it's not only simpler and shorter, but you can conditionally target different devices such as smartphones and tablets separately if necessary without having to add any dummy elements into the DOM.
However, above code doesn't take into account the case for laptops with touchscreen. What you are doing by wanting to detect a mobile device is getting a little too close to a “browser sniffing” concept IMO.
All that being said, I think your best bet is to either redirect or write a different script to the output using a server-side language (if that is an option). Since you don't really know the capabilities of a mobile browser x, doing the detection, and alteration logic on the server side would be the most reliable method.
Of course, all of that is a moot point if you can't use a server side language :) Sometimes it is desired to know which brand device a client is using in order to show content specific to that device, like a link to the iPhone store or the Android market.
iPads and Android tablets will return numbers like 768, so they'll get the full view like you'd want. UserAgent, not every device reveals its real OS.
However, I prefer using a combination of Modernize.touch and user agent testing, just to be safe. Also note that testing the user agent immobile will give you broader range of detected Microsoft mobile devices than Windows Phone.
For instance in Bootstrap's (Mobile First) Media Queries, there exist 4 snap/break points: If the user agent contains 'Mob' (as per MDN) and ontouchstart is available then it is likely to be a mobile device.
And if you need to detect the tablets as well, just check About section for additional Regex parameter. Android tablets, iPads, Kindle Fires and Playbooks are not detected by design.
Check out this post, it gives a really nice code snippet for what to do when touch devices are detected or what to do if touch start event is called: I would be suggesting to use following combo of strings, to check if device type being used.
As per Mozilla documentation string Mob is recommended. Similarly, for being on the safe side iPad and iPhone strings could also be used to check the device type.
Earn 10 reputation in order to answer this question. The reputation requirement helps protect this question from spam and non-answer activity.
Ideally, this header would give servers the ability to perform content negotiation, sending down exactly those bits that best represent the requested resource in a given user agent, optimizing both bandwidth and user experience. In practice, however, this header’s value exposes far more information about the user’s device than seems appropriate as a default, on the one hand, and intentionally obscures the true user agent in order to bypass misguided server-side heuristics, on the other.
There’s quite a bit of information packed into those strings (along with a fair number of lies). Are all broadcast along with every request, and form the basis for fingerprinting schemes of all sorts.
Individual vendors have taken stabs at altering their user agent strings, and have run into a few categories of feedback from developers that have stymied historical approaches: Brand and version information (e.g. “Chrome 69”) allows websites to work around known bugs in specific releases that aren’t otherwise detectable.
For example, implementations of Content Security Policy have varied wildly between vendors, and it’s difficult to know what policy to send in an HTTP response without knowing what browser is responsible for its parsing and execution. Developers will often negotiate what content to send based on the user agent and platform.
Similarly to #1, OS revisions and architecture can be responsible for specific bugs which can be worked around in website’s code, and narrowly useful for things like selecting appropriate executables for download (32 vs 64 bit, ARM vs Intel, etc). This document proposes a mechanism which might allow user agents to be a bit more aggressive about removing entropy from the User-Agent string generally by giving servers that really need some specific details about the client the ability to opt-into receiving them.
It introduces four new Client Hints () that can provide the client’s branding and version information, the underlying operating system’s branding and major version, as well as details about the underlying device. Rather than broadcasting this data to everyone, all the time, user agents can make reasonable decisions about how to respond to given sites' requests for more granular data, reducing the passive fingerprinting surface area exposed to the network.
The request header field gives a server information about the architecture of the platform on which a given user agent is executing. The request header field gives a server information about the device on which a given user agent is executing.
The request header field gives a server information about the platform on which a given user agent is executing. The request header field gives a server information about the platform version on which a given user agent is executing.
The request header field gives a server information about a user agent's branding and version. The value of each item SHOULD include a “v” parameter, indicating the user agent's version.
It is considered low entropy because it includes only the user agent's branding information, and the significant version number (both of which are fairly clearly sniffable by “examining the structure of other headers and by testing for the availability and semantics of the features introduced or modified between releases of a particular browser” ). It is considered low entropy because it is a single bit of information directly controllable by the user.
Collect pairs of brands and which represent the user agent, its equivalence class and/or its rendering engine. Append additional items to list containing objects, initialized with arbitrary and combinations.
Note: One approach to minimize caching variance when generating these random components could be to determine them at build time, and keep them identical throughout the lifetime of the user agent's significant version. Client Hints will not be delivered to non-secure endpoints (see the secure transport requirements in Section 2.2.1 of).
The primary goal of User Agent Client Hints is to reduce the default entropy available to the network for passive fingerprinting. User agents ought to exercise judgement before granting access to this information, and MAY impose restrictions above and beyond the secure transport and delegation requirements noted above.
For instance, user agents could choose to reveal only on requests it intends to download, giving the server the opportunity to serve the right binary. The header, however, is likely to be impossible to remove entirely in the near-term, as existing sites' content negotiation code will continue to require its presence (see for a recent example of a new browser’s struggles in this area).
One approach which might be advisable could be for each user agent to lock the value of its User-Agent header, ensuring backwards compatibility by maintaining the crufty declarations of “like Gecko” and “Apple WebKit/537.36” on into eternity. This can ratchet over time, first freezing the version number, then shifting platform and model information to something reasonably generic in order to reduce the fingerprint the header provides.
History has shown us that there are real incentives for user agents to lie about their branding in order to thread the needle of sites' sniffing scripts, and prevent their users from being blocked by UA-based allow/block lists. Resetting expectations may help to prevent abuse of the UA string’s brand in the short term, but probably won’t help in the long run.
User agents brands containing more than a single entry could encourage standardized processing of the UA string. By randomly including additional, intentionally incorrect, comma-separated entries with arbitrary ordering, they would reduce the chance that we ossify on a few required strings.
In order to encourage sites to rely on equivalence classes based on Chromium versions rather than exact UA sniffing, Chrome might remove itself from the set entirely. Browsers based on Chromium may use a similar UA string, but use their own brand as part of the set, enabling sites to count them.
When adding arbitrary values to brands, user agents MUST make sure that receivers of the header adhere to Structured Header parsing, by adding escaped double-quotes, commas and semi-colons to those values. The purpose of this is to make non-compliant server implementations immediately aware that their parsing code is inadequate.
The User Agent Class provides functions that help identify information about the browser, mobile device, or robot visiting your site. The User Agent class is always available directly from the current IncomingRequest instance.
By default, you will have a request instance in your controller that you can retrieve the User Agent class from: When the User Agent class is initialized it will attempt to determine whether the user agent browsing your site is a web browser, a mobile device, or a robot.
If you find that some bots that commonly visit your site are missing from the list you can add them to your app/Config/UserAgents.php file. IsReferral () Returns:TRUE if the user agent is a referral, FALSE if return type:boolReturns TRUE/FALSE (boolean) if the user agent was referred from another site.
GetVersion () Returns:Detected browser version or an empty stringReturn type:stringReturns a string containing the version number of the web browser viewing your site. GetMobile () Returns:Detected mobile device brand or an empty stringReturn type:stringReturns a string containing the name of the mobile device viewing your site.
GetPlatform () Returns:Detected operating system or an empty stringReturn type:stringReturns a string containing the platform viewing your site (Linux, Windows, OS X, etc. Return type:Parses a custom user-agent string, different from the one reported by the current visitor.
Google's Chrome team has delayed its User-Agent Client Hints (UA-CH) makeover until at least 2021 due to the impact of the COVID-19 coronavirus on the web development ecosystem. “While work on UA-CH continues, we don’t currently know in what ways or for how long COVID-19 will impact the web ecosystem’s ability to test and implement support for this change,” said Yo av Weiss, Google developer advocate, in a forum post on Monday.
The string contains details about the client's software and hardware and can be used legitimately, to tailor content to the capabilities of the receiving device. “There’s quite a bit of information packed into those strings (along with a fair number of lies),” the W3C's User-Agent Client Hints draft explains.
As with other web tech changes backed by the ad biz, like its Manifest v3 extension platform revision and its SameS ite cookie system, the info thinning aspect of the UA-CH project will be disruptive. Initially, it was supposed to debut in Chrome 81 (itself delayed from mid-March until April 7), but after receiving feedback, Google wanted to hold off a bit longer.
The idea is that the browser will be able to make decisions about whether to fulfill information requests returned to the server's initial response. “If this change is implemented, then advertisers will no longer be able to verify their adverts were served to humans when displayed in this manner by publishers,” wrote James Roswell, CEO of mobile detection biz 51Degrees last week in a GitHub issues post for the UA-CH spec.
The concern is that Google will provide privacy protections that limit every ad biz except for itself, because it can identify users through its other services.