If you're often juggling APK files for backups or sideloading, you might occasionally get things mixed up. Or you might want to ensure that nothing looks fishy. In either case, there is a nifty little Windows program called APK-Info that tells you all about an APK.
When you launch APK-Info it asks you to select an APK file. It extracts the package name, permissions, API level, version, and lets you open the Play Store page. You can even automatically switch to a simplified file name from this interface.
The program is totally free, originally posted on the Total Commander forums, but updated by an XDA user. Grab it below.