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.

Download the Java Software Development Kit (Java SDK) at Oracle’s official website;
Open the Terminal using Spotlight or the LaunchPad, on MacOS, or by pressing Ctrl+Alt+T on the majority of Linux distros;
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

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
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!
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!
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.