Android: How to find which platform version an APK targets?

Use aapt:

aapt list -a package.apk | grep SdkVersion

You will see version numbers in hex. e.g.:

  A: android:minSdkVersion(0x0101020c)=(type 0x10)0x3
  A: android:targetSdkVersion(0x01010270)=(type 0x10)0xc

For this apk, minSdkVersion is 0x3 i.e. 3, and targetSdkVersion is 0xc i.e. 12.