APK Downloader is a Google Chrome extension / Firefox addon that allows you to download Android APK files from Google Play Store (Android Market) to your PC.

Features:

• Easy to setup
• Download instantly APK files from Google Play server, so it’s faster ( if not fastest ) than any third-party web sites.
• Download .OBB files ( APK Expansion files ) from games.
• Support both Chrome and Firefox.

Download:Use at your own risk. 
– APK Downloader for Chrome
– APK Downloader for Firefox

For more information visit official site at
http://codekiem.com/2014/08/07/official-apk-downloader-v2-download-apk-files-from-google-play-store-to-pc/#apk_changelogs