Market Helper is an app that lets you 'trick' your device so it 'thinks' it's a different model than it actually is. This lets you download and run certain app that aren't compatible with your Android as is. For instance, you can make your Nexus 7 believe it's a Samsung Galaxy S3, which will allow you to download lots of apps you normally couldn't on your tablet, such as WhatsApp.
Market Helper works in a very simple way. You have to choose if you want to turn your device into a tablet or mobile phone, and then which exact model. You can transform your device into a Nexus 5, Samsung Galaxy S3, Sony Xperia, or Nvidia Shield, among many others.
The best thing about Market Helper is that you don't need to reset your device to activate it. After just a few seconds, your Android device will be 'tricked'. You can restore previous settings directly from the application when you no longer need the 'trick', or just restart your device.
Market Helper is a useful and interesting tool that lets you use apps you normally wouldn't be able to. That said, keep in mind that you'll need a rooted device to be able to use it.
Editors' Note: To download the application, click on “Download” button. Enter your log in details. When download is completed, go to your app bar, click Downloads and find the file you just downloaded. Open the file and press “Install”. Please note that this download may not be available in some countries.
Read the instructions about the installing and removing the apps here