Xcode - Xcode is Apple’s powerful integrated development environment for creating great apps for Mac, iPhone, and iPad. Xcode 4 includes the Xcode IDE, instruments, iOS Simulator, and the latest Mac OS X and iOS SDKs.
F-Droid - F-Droid is an interesting alternative for Android users who want to try something different and not have to use the Goole Play store all the time.
Android Studio - Android development environment based on IntelliJ IDEA
APK Pure - Download apk for Android with APKPure APK downloader. NoAds, Faster apk downloads and apk file update speed. Best of all, it's free
Adobe AIR - Adobe® AIR® runtime enables developers to package the same code into native apps for Windows and Mac OS desktops, iPhone, iPad, Kindle Fire, Nook Tablet & Android. Buy now.
APKMirror - Android Market and APK Downloads