Using Proguard to deobfuscate code

TLDR; Optimisation features of Proguard can be useful for removing some "obfuscations" that add dead code and screw up control flow.

Proguard comes with Android Studio or can be installed from homebrew on Mac, that one version is newer:

$brew install proguard

Then use a generic script similar to this one:

-injars      <obfuscated jar>
-outjars     <result>
-libraryjars $HOME/Library/Android/sdk/platforms/android-19/android.jar ; or similar
-optimizationpasses 10 
-dontobfuscate
-dontpreverify
-printusage

-dontusemixedcaseclassnames
-dontskipnonpubliclibraryclasses
-verbose

-keepattributes *Annotation*

 
-keep public class * extends android.app.Activity
-keep public class * extends android.app.Application
-keep public class * extends android.app.Service
-keep public class * extends android.content.BroadcastReceiver
-keep public class * extends android.content.ContentProvider
-keep public class * extends android.app.admin.DeviceAdminReceiver
-keep public class * extends android.view.View {
 public <init>(android.content.Context);
        public <init>(android.content.Context, android.util.AttributeSet);
 public <init>(android.content.Context, android.util.AttributeSet, int);
 public void set*(...);
}
-keepclasseswithmembers class * {
 public <init>(android.content.Context, android.util.AttributeSet);
}
-keepclasseswithmembers class * {
 public <init>(android.content.Context, android.util.AttributeSet, int);
}
-keepclassmembers class * extends android.content.Context {
 public void *(android.view.View);
 public void *(android.view.MenuItem);
}
-keepclassmembers class * implements android.os.Parcelable {
 static ** CREATOR;
}
-keepclassmembers class **.R$* {
 public static <fields>;
}
-keepclassmembers class * {
 @android.webkit.JavascriptInterface <methods>;
}
-keepclasseswithmembernames class * {
    native <methods>;
}
-keepclassmembers enum * {
    public static **[] values();
    public static ** valueOf(java.lang.String);
}
-dontwarn android.support.**

Run as proguard @deob.conf and you'll end up with a more readable version of your obfuscated code.