jbalde

UserAgent Theme Switcher is a simple plugin which lets you change the theme to be displayed according to the detected browser.
Checks from a predefined list useragent so that the user can at will change the theme shown for that browser. 
A user can configure a special theme for example for mobile phones that is lighter and this adapted to these devices
Ideal for displaying themes ready to opera mobile, internet explorer mobile, iphone, android, etc.
Now the cache is not supported but will work so that if it is supported in the future

UserAgent Theme Switcher

UserAgent Theme Switcher is a simple plugin which lets you change the theme to be displayed according to the detected browser

Markus Wiesenhofer

Polylang is a fantastic plugin to make WordPress multilingual. The Polylang extension enables you to detect the preferred language according on the country.
If your website contains 2 different locales with the same language (e.g. de_DE for German/German and de_AT for German/Austria) then Polylang automatically sets the language according to the browser settings.
Austrian website visitors who have set their operating system / browser to Germany (e.g. the Devices was buyed in Germany) will always be redirected to de_DE.
This Plugin detects the preferred language according on the visitors country and will set the language correct to de_AT.
Please notice that the IP API is only for non-commercial use allowed.
<h4>Required Plugin</h4>
<ul>
<li><a href="https://polylang.pro" rel="nofollow ugc">Polylang Pro</a> by WP SYNTEX – Polylang allows you to create a bilingual or multilingual WordPress site.</li>
</ul>

Polylang – Country Detection

This plugin detects the preferred language according on the country.

UserAgent Theme Switcher vs Polylang – Country Detection