Your application’s signature is a certification method that allows you to define and identify the author of the app and update it in a simple and quick way.

How to sign your APK using MacOS X / Linux

Setting up

Java’s Software Development Kit (JSD) is required to sign an APK file. If you already installed JSD, go to the second step.

1. Download the Java Software Development Kit (Java SDK) at Oracle’s official website (click here);

2. Open the Terminal using Spotlight or the LaunchPad, on MacOS, or by pressing Ctrl+Alt+T on the majority of Linux distros;

3. Type in the following command “jarsigner”

   • If the Terminal returns a “command not found” error, please try to re-install the SDK;
   • If the Terminal returns a list of arguments for jarsigner, you have successfully installed Java SDK.

Signing the APK

1. While in the Terminal, type in the following command with the arguments:

   • jarsigner -keystore <path to the keystore file> <path to the unsigned APK> <keystore alias>
   • Example: jarsigner -keystore /Users/Aptoide/Signature.jks /Users/Aptoide/Downloads/Sign_blank_APK_to_certify_com.example.catappult.apk Signature

2. You must use the same Keystore used to sign the APK you want to submit. Signatures from this blank APK and your APK must match.

3. You will be asked to insert the password for your Keystore file, type it down and press enter. Your password is being inserted even if no text is shown.

4. If everything went right, the unsigned APK will be signed and you can now submit it

   • If an error occurred, jarsigner will let you know what happened. Please, read carefully the information it returns so you can complete the process successfully.

How to sign your APK using Windows 10

Setting up

apksigner is a tool that allows you to sign APKs, which is available as part of Android SDK Build Tools (you can find it inside the "build-tools" folder in the Android SDK installation folder). To know more about this tool visit the official documentation page here.

Signing the APK

1. While in the Command Prompt, type in the following command, but with the following arguments:

apksigner sign -v --ks <path to the keystore file> <path to the unsigned APK>
    * Example: apksigner sign -v --ks “C:\Users\Aptoide\Signature.jks “C:\Users\Downloads\Unsigned_Test.apk”

2. You must use the same Keystore used to sign the APK you want to submit. Signatures from this blank APK and your APK must match!

3. You will be asked to insert the password for your Keystore file, type it down and press enter. Your password is being inserted even if no text is shown!