How to Modify or Hack android APK files [No Root]

APKTool to decompile and compile APK files
SignApk to sign the recompiled APK files

I have uploaded the above files into a ZIP file. You can download it from HERE
Thanks to those guys who made APKTool and SignAPK. Actually I referred to Xda forum for the above tools. After downloading the files, follow the steps below.

Extract the files and open command prompt in the extracted folder. There will be four folders.

files , compiled, decompiled, and signed.
Files > Place your working APKs here

Decompiled > The files after Decompiling your APK will go here. You can edit the files after decompiling.

Compiled > After editing and recompiling, the unsigned APK file goes here. You cant use it before signing.

Signed > Finished APK, after signing goes here. You can install the APK after signing.
Place the working APK into the Files folder and type the following command in the command prompt:

(Here I'm taking hill climb racing as an example. You can take any game)

The command is very simple. It says apktool to decompile the file which is situated in files/hill.apk and save the decompiled files to decompiled/hill folder (d is the command for decompile)

Now, just go through the files in the decompiled folder. It is very easy to mod. Here,I want to change the driver head of Hill Climb racing. So, in the assets folder., there is an driver-head.png file. It is obvious that this is the driver head image file. Now, edit the image using Photoshop (or anything similar) and change the head. Here, I have downloaded a photo from Google (dont know whose head is that! maybe an actress!!) replaced the head with this one and that's enough!. Be careful, when doing this, the photo should be in correct position. I mean, The Head should be above the neck and not should be in the AIR! I'm just doing this for this tutorial. If you want, you can change cars, tires etc. Also try editing the manifest file and other folders. In manifest file, you can edit the App name, version, etc.

Now time to recompile.

For recompiling, open command prompt and type the following command

I think there is no need of an explanation here. Command b is for Binding, I think.
Now the final step. To sign the APK file, you can use the SignApk (Provided in the Zip file). Type the following command

Now transfer it to the Phone and Test it. Enjoyyy!

After decompiling, you get the java files as .smali files. It is very difficult to edit it. If you try, you can do much more.

Here is the screenshot of what I have done

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