Katsushi Kawamori

<ul>
<li>Switch the theme by the user agent.</li>
<li>Can be specified user agent by a regular expression.</li>
<li>Can add types and set the corresponding user agent.</li>
<li>Sibling plugin -> <a href="https://wordpress.org/plugins/useragent-content-switcher/" rel="ugc">UserAgent Content Switcher</a>.</li>
</ul>

UserAgent Themes Switcher

Switch the theme by the user agent. Can be specified user agent by a regular expression.

kyleabaker

WP-UserAgent is a simple plugin that allows you to display details about a computer’s <a href="http://en.wikipedia.org/wiki/Operating_system" rel="nofollow ugc">operating system</a> or <a href="http://en.wikipedia.org/wiki/Web_browser" rel="nofollow ugc">web browser</a> that your visitors comment from.
It uses the comment->agent property to access the <a href="http://en.wikipedia.org/wiki/User_agent" rel="nofollow ugc">User-Agent string</a>. Through a series of regular expressions, this plugin is able to detect the operating system and browser which can be integrated in comments or placed in custom places through your template(s).
I’m adding new web browsers and operating systems frequently, as well as updating and optimizing the source code. Your feedback is very important, new features have been added by request, so if there’s something you would like to see in WP-UserAgent, <a href="https://www.kyleabaker.com/goodies/coding/wp-useragent/" rel="nofollow ugc">leave a comment</a>, and I’ll see what I can do.
WP-UserAgent was written with Geany – <a href="http://www.geany.org/" rel="nofollow ugc">http://www.geany.org/</a> 
Images created with The Gimp – <a href="http://www.gimp.org/" rel="nofollow ugc">http://www.gimp.org/</a>
<h3>Features</h3>
<ul>
<li>Detects most web browsers and popular operative systems (if you find one missing, please <a href="https://www.kyleabaker.com/goodies/coding/wp-useragent/" rel="nofollow ugc">let me know</a>!)</li>
<li>Shows web browser and operating system icons, names, and a link to their homepages (this will be customizable in future versions).</li>
<li>Shows web browser and operating system in the Admin comments management page (unless you’re using “custom” option).</li>
<li>Customizable, has its own Options Page where you can change the size of the web browser and operating system icons, where you want it to be displayed, and a few other options.</li>
<li>Option to only display web browser and operating system info in Admin section</li>
<li>Updated frequently to further extend web browser and operating system detection as well as source code improvements.</li>
<li>Published under GPLv3</li>
</ul>
Some of you may compare this to another well-known plugin named browsersniff. WP-UserAgent is a heavily modified and improved version of UserAgent-Spy, with several improvements over browsersniff also:
<ul>
<li>Easy standard installation, just upload to wp-plugins and activate it.</li>
<li>Customizable options.</li>
<li>No basic knowledge of PHP or editing WordPress templates required.</li>
<li>Published under GPLv3.</li>
</ul>

WP-UserAgent

WP-UserAgent is a simple plugin that allows you to display details about a computer's operating system or web browser that your visitors comment  …

UserAgent Themes Switcher vs WP-UserAgent