thingsym

Multi Device Switcher plugin allows you to set a separate theme for device (Smart Phone, Tablet PC, Mobile Phone, Game and custom). 
This plugin detects if your site is being viewed by UserAgent, and switches to selected theme. 
The Custom Switcher can add every device.
<h4>Features</h4>
<ul>
<li>Set a separate theme for device (Smart Phone, Tablet PC, Mobile Phone, Game), switches to selected theme.</li>
<li>Add every device by the Custom Switcher.</li>
<li>Add links ‘Mobile’ or ‘PC’ in the theme by the PC Switcher, switch to the default theme.</li>
<li>Switch the content of the post or page for each device by the Display Switcher Shortcode.</li>
<li>Disable the switching of the theme for each url by the Disable Switcher.</li>
<li>Can be using is_multi_device() function that detect of the device.</li>
<li>Multi Device Switcher Command command-line tool (required WP-CLI)</li>
</ul>
<h4>Support</h4>
If you have any trouble, you can use the forums or report bugs.
<ul>
<li>Forum: <a href="https://wordpress.org/support/plugin/multi-device-switcher/" rel="ugc">https://wordpress.org/support/plugin/multi-device-switcher/</a></li>
<li>Issues: <a href="https://github.com/thingsym/multi-device-switcher/issues" rel="nofollow ugc">https://github.com/thingsym/multi-device-switcher/issues</a></li>
</ul>
<h4>Contribution</h4>
Small patches and bug reports can be submitted a issue tracker in Github. Forking on Github is another good way. You can send a pull request.
Translating a plugin takes a lot of time, effort, and patience. I really appreciate the hard work from these contributors.
If you have created or updated your own language pack, you can send gettext PO and MO files to author. I can bundle it into plugin.
<ul>
<li><a href="https://github.com/thingsym/multi-device-switcher" rel="nofollow ugc">VCS – GitHub</a></li>
<li><a href="https://wordpress.org/plugins/multi-device-switcher/" rel="ugc">Homepage – WordPress Plugin</a></li>
<li><a href="https://translate.wordpress.org/projects/wp-plugins/multi-device-switcher" rel="nofollow ugc">Translate Multi Device Switcher into your language.</a></li>
</ul>
You can also contribute by answering issues on the forums.
<ul>
<li>Forum: <a href="https://wordpress.org/support/plugin/multi-device-switcher/" rel="ugc">https://wordpress.org/support/plugin/multi-device-switcher/</a></li>
<li>Issues: <a href="https://github.com/thingsym/multi-device-switcher/issues" rel="nofollow ugc">https://github.com/thingsym/multi-device-switcher/issues</a></li>
</ul>
<h4>Patches and Bug Fixes</h4>
Forking on Github is another good way. You can send a pull request.
<ol>
<li>Fork <a href="https://github.com/thingsym/multi-device-switcher" rel="nofollow ugc">Multi Device Switcher</a> from GitHub repository</li>
<li>Create a feature branch: git checkout -b my-new-feature</li>
<li>Commit your changes: git commit -am ‘Add some feature’</li>
<li>Push to the branch: git push origin my-new-feature</li>
<li>Create new Pull Request</li>
</ol>
<h4>Contribute guidlines</h4>
If you would like to contribute, here are some notes and guidlines.
<ul>
<li>All development happens on the develop branch, so it is always the most up-to-date</li>
<li>The master branch only contains tagged releases</li>
<li>If you are going to be submitting a pull request, please submit your pull request to the develop branch</li>
<li>See about <a href="https://help.github.com/articles/fork-a-repo/" rel="nofollow ugc">forking</a> and <a href="https://help.github.com/articles/using-pull-requests/" rel="nofollow ugc">pull requests</a></li>
</ul>
<h4>Test Matrix</h4>
For operation compatibility between PHP version and WordPress version, see below <a href="https://github.com/thingsym/multi-device-switcher/actions" rel="nofollow ugc">Github Actions</a>.
<h4>Known bugs</h4>
WordPress Core version 6.4 – 6.4.1
<ul>
<li>Theme doesn’t switch properly</li>
<li>Bug report: https://core.trac.wordpress.org/ticket/59847</li>
<li>It seems to have been caused by a change (breaking change) at https://core.trac.wordpress.org/changeset/56635. The bug is fixed in https://core.trac.wordpress.org/changeset/57129 (fixed in WordPress 6.4.2)</li>
</ul>

Multi Device Switcher

WProger

Multi Device Switcher plugin allows you to set a separate theme for device (Smart Phone, Tablet PC, Mobile Phone, Game and custom).

Tubal

A lightweight detector of mobile devices, OSs & browsers that, optionally, allows your site to switch to a mobile theme when a mobile device is detected or when your users feel like it.
This plugin adds the class MobileDTS to WordPress.
<h4>Mobile Detection</h4>
On every request, this plugin will try to detect if the user is viewing your site with a mobile device or not. If he is, the detector will also give you some info about the device, browser and OS used.
Who will be happy with this detector?
If you need a fast and reliable way to detect if a user is visiting your site with a mobile device, then you’ll be happy. However, if you need precise information about the device used (other than OS and browser) such as screen resolution you need a detector such as <a href="http://deviceatlas.com/" rel="nofollow ugc">DeviceAtlas</a> or <a href="http://wurfl.sourceforge.net/" rel="nofollow ugc">WURFL</a>.
How to query the detector?
Use the method <code>MobileDTS::is($key)</code>. <code>is()</code> returns boolean <code>true</code> or <code>false</code>.
Example:
<pre><code><?php

if (MobileDTS::is('android')) {
 // User with a mobile device running Android OS
} else if (MobileDTS::is('ios')) {
 // User with a mobile device running iOS
} else if (MobileDTS::is('mobile')) {
 // User with a mobile device (any, even 10 years old mobile phones) 
} else {
 // User with a desktop device 
}

?>
</code></pre>
Available keys:
<ul>
<li><code>mobile</code> (Is it a mobile?)</li>
<li><code>other</code> (Any other mobile device)</li>
</ul>
Popular mobile devices
<ul>
<li><code>iphone</code> (Apple iPhone)</li>
<li><code>ipad</code> (Apple iPad)</li>
<li><code>kindle</code> (Amazon Kindle)</li>
</ul>
Mobile OS
<ul>
<li><code>android</code> (Android OS)</li>
<li><code>bada</code> (Bada OS)</li>
<li><code>bbos</code> (Blackberry OS)</li>
<li><code>ios</code> (Apple iOS)</li>
<li><code>palmos</code> (Palm OS)</li>
<li><code>symbian</code> (Symbian OS)</li>
<li><code>webos</code> (Hp WebOS)</li>
<li><code>windows</code> (Windows Phone OS and older)</li>
</ul>
Mobile browsers
<ul>
<li><code>ff_mobile</code> (Mozilla Fennec & Firefox mobile)</li>
<li><code>ie_mobile</code> (IE mobile)</li>
<li><code>netfront</code> (NetFront)</li>
<li><code>opera_mobile</code> (Opera Mobile or Mini)</li>
<li><code>uc_browser</code> (UC Browser)</li>
<li><code>webkit_mobile</code> (Webkit mobile)</li>
</ul>
<h4>Theme Switching</h4>
You can configure your site to automatically switch to a mobile theme when a mobile device is detected or when the user requests it (on demand).
Once the plugin is installed, a new submenu titled <code>Mobile Detector</code> is added under the <code>Settings</code> menu.
Theme switching is disabled by default. To enable theme switching simply select a theme to use as your mobile theme and the plugin will take care of the rest.
This plugin assumes your active theme is optimized for desktop screens only. So, if you’re using a responsive theme that adapts to any screen size you shouldn’t use the theme switching feature (don’t select a theme).
How it works:
<ul>
<li>On each page load, this plugin checks for the existence of a cookie that stores which theme (mobile-optimized or desktop-optimized) the user prefers to browse.</li>
<li>If the cookie exists, the theme the user expects will be displayed.</li>
<li>If the cookie does not exist (first-time visitor), this plugin checks whether the user is visiting your site with a mobile device or not and, if he is, your mobile-optimized theme will be used. Afterwards, a cookie will be set to store the user’s “initial preference”.</li>
<li>Anytime the user switches (you must create a link/button in your theme using the Template functions below) between themes, the cookie is updated with his preference so the site version (theme) the user expects will be displayed on future visits.</li>
</ul>
Template functions
<ul>
<li>
<code>MobileDTS::get_switch_theme_link()</code> Returns the current URL with an additional <code>switch_theme</code> parameter (set automatically to ‘mobile’ or ‘desktop’). You’ll need this function to create a link/button that allows users to switch between the desktop and mobile themes. See example below.
</li>
<li>
<code>MobileDTS::switch_theme_link()</code>: same as above but this one outputs the URL instead of returning it. URL is escaped.
</li>
<li>
<code>MobileDTS::get_switch_theme_name()</code> returns the type of the theme to switch to (either ‘mobile’ or ‘desktop’). Use this method together with <code>get_switch_theme_link()</code>. The type can be translated to your language (plugin uses wp’s <code>__()</code> function for ‘mobile’ & ‘desktop’ strings).
</li>
<li>
<code>MobileDTS::switch_theme_name()</code> same as above but this one outputs the type instead of returning it.
</li>
<li>
<code>MobileDTS::is_mobile_theme()</code> tells you wether your site is displaying to the user the mobile theme or not. Returns boolean <code>true</code> or <code>false</code>.
</li>
<li>
<code>MobileDTS::is_switcher_enabled()</code> tells you wether theme switching is disabled or not. Returns boolean <code>true</code> or <code>false</code>.
</li>
</ul>
Creating a ‘Switch to …’ link
Let’s create a switch link to allow the user to switch between the 2 versions of a site (themes):
<pre><code><?php if (MobileDTS::is_switcher_enabled()): // Optional but useful if you need to disable theme switching for a while. ?>

<a href="<?php MobileDTS::switch_theme_link() ?>">Switch to the <?php MobileDTS::switch_theme_name() ?> version of this site</a>

<?php endif; ?>
</code></pre>
Paste that code in your templates (usually in <code>header.php</code> and/or <code>footer.php</code>), enable theme switching and play a little.
Let’s suppose a user is viewing the site (http://example.com/home) for the first time with a mobile device and theme switching is enabled. The above code would output this link:
<pre><code><a href="http://example.com/home?switch_theme=desktop">Switch to the desktop version of this site</a>
</code></pre>

Mobile Detector

Nice and Simple

Lightweight detector of mobile devices, OSs & browsers. Optionally a mobile theme switcher.

Multi Device Switcher vs Mobile Detector