If you want to try Experiments with Android Apps then you have to learn, How to Modify Android Apk Apps.
And If you want to create a mod Apk then you have to learn, How to unpack and repack Apk File.
You can unpack Apk File by using Apk Decompiler App. Besides that, you can Also try Zip File Extractor for Android.
But You don't need Apk Extractor or Apk Editor App to unpack and Repack Android Apk Apps.
You can unpack and repack Apk Files by using a Simple File Manager Application on Android device.
But Before that, You need to understand the Need and Benefits of repacking or Unpacking Apk File.
Benefits of Unpacking and repacking Apk File From Android
Note: You can't Modify Android App of Anyone for Personal use, It's Illegal. This Tutorial is for Educational Purpose Only.
But You can Learn, How to unpack and repack Apk file on Android. This Tutorial will Definitely help you to modify your own Android Apk File.
Suppose, You've Created an own Android Application by using Free App Builder Platforms. So, You can modify your own Apk App from Android phone.
If you want to Create a Free Android App for your Business or Personal use.
Unpack Apk File and try experiments as much as you can because you even don't need a Computer to Modify an Android App.
How to Unpack Apk File on Android
1 Install Es File Explorer From Google Play. Es File Explorer is a File Manager Application available on Google play for free.
Install Es File Explorer From Google Play
3 Choose Path for Extract Apk. Select the path to Extract selected files on the desired Folder. I suggest you, select an empty Folder because extracting will convert the Apk File into many Files and Folders. So, its good to select an empty folder for easy to located the Files and Folder of Apk.
4 Open Extracted Folder. After Extracting the Apk File You will get a Folder, simply open the Folder to see what is inside.
5 Apk is Unpacked. Now, your Apk is unpacked into Files and Folders. You can edit all Files. Modify the Files then read the repacking process below.
How to Repack Apk File on Android
1 Select All Files and Folders. To select All Files in Es File Explorer, Tap and Hold any File or Folder then Click on Select All option located on the Top.
2 Click on More >>Compress. After Selected All the Files and Folders, Click on More Located on the Below Right Corner then Click on Compress.
Compression Will Compress all the Files and Folder into the Zip File.
3 Click OK. In this step, Simply click on OK because of Zip Compression Format is already set as default.
4 Rename Zip File. You will get the Zip File after completing the process of compression. Select the Zip File and Click on Rename.
5 Replace .zip with .apk. We need to Change the File Extension from .zip to .apk
6 Apk is Repacked. After changing the File Extension, you will get the modified Android App.
Now you can delete All these Files and Folders because you've created an Apk from these Files and Folders. Whenever you want to edit or modify the Apk File again, you can edit this Apk File.