Detect is a fairly complete wrapper for the Mobile_Detect library by @serbanghita.

The plugin exposes most of Mobile_Detect's methods, and can be used in your Twig:

{{ craft.detect.isMobile ? 'I am mobile.' : 'I am not mobile.' }}

...or as a PHP service:

$isMobile = craft()->detect->isMobile();

1. Unzip
2. Drop the /detect folder inside your /craft/plugins directory
3. Install in the Craft CP

isMobile

Detects all mobile devices, both phones and tablets

isTablet  
isPhone

isiOS  
isAndroidOS  
isBlackBerryOS  
isPalmOS  
isSymbianOS  
isWindowsMobileOS   
isWindowsPhoneOS  

is(key)

Test for anything, e.g. is('iphone')

match(pattern)

Test using regular expressions

version(component)

Get the version of a component, e.g. version('iPhone')

mobileGrade

Get browser grade (e.g. "A")

getScriptVersion

Prints the MobileDetect library's version

getUserAgent  
setUserAgent(userAgent)  
getMobileHeaders  
getHttpHeaders    
setHttpHeaders(httpHeaders)  
getCfHeaders  
setCfHeaders(cfHeaders)  

Initial release

This Craft CMS plugin is free, and you can do whatever you want with it. The author takes no responsibility for any data loss or other issues resulting from the use of this plugin.

Kindly report any issues here, but please note that no promises are made regarding response time, bug fixes or feature request implementations.

Pull requests are very welcome!