ad1 Allowing Non-Market Apps

You’ll have to enable the “Unknown Sources” option in the Applications settings screen.



Amazon Appstore

Amazon’s app store maybe the most well-known alternative to the Android Market. It’s included by default on the Kindle Fire . The big drawback to this app store is that it’s only available in the US.

GetJar

GetJar isn’t as well-known, but it’s available everywhere. GetJar also gives away paid apps for free. Unlike Amazon’s app giveaways, GetJar’s paid app giveaways don’t expire. GetJar adds new paid apps to its free “Gold Apps” section every week.

AppBrain
AppBrain takes a different, more social approach to an app store. It sells itself as an app recommendation system. With its social features, you can friend people and view your friends’ favorite apps. You can also see the apps that are currently hot, site-wide.

AppBrain’s recommendation engine scans your device and, based on what you currently have installed, gives you personalized app recommendations.

SlideME
It’s preloaded on a variety of devices, particularly in regions where the Android Market isn’t available.

SlideME provides a large collection of both paid and free apps. When you buy an app on SlideME, SlideME gives a higher percentage of the revenue to the developer than Google does for the Android Market.

Opera App Store
You’ll find a link to it on Opera Mobile’s default speed dial page. Opera acquired its app store though a purchase of Handster in 2011. The store contains Android apps, in addition to apps for other platforms. You can access it through a browser on your device, or use a browser on your PC and download app APK files to your computer.

Info From 

http://www.howtogeek.com/106175/the-top-5-alternatives-to-the-android-market/ ad2

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