Sysdev has just released a new update for Kalipso 5 with the capability for compiling your Apps with the Android App Bundle format.

Sysdev has just released a new update for Kalipso 5 with the capability for compiling your Apps with the Android App Bundle format. In August 2021 all new Apps submitted to Google Play will be required to be submitted with the Android App Bundle format.

You can read more about this here:

Google Play Policies | Android Developers

What changes for Apps developed with Kalipso?

For Kalipso developers there is no need to make any modification in your Apps.

When you deploy your App and generate an APK, there is a new option to also generate the Android App Bundle.

This new option will also generate a new file with .aab (android app bundle) file extension that you can use to submit your App to Google Play.

How is .aab file submission to Google Play different from .apk?

When you compile an APK, this APK is signed with a private key, and in Google Play there were 2 options: you could choose to handle the signature yourselves, and the APK that was available on Google Play contained your original signature, or you could choose to let Google handle the signature, and before releasing the App to Google Play, Google would re-sign your APK.

Using the AAB format, you no longer have the option to handle your APK signing, Google will have the App private key, Google will generate APKs from the AAB file you submitted and then Google will sign the APKs with the private key.

When you create your App in Google Play console and you create your first submission, there are several options that you should be aware of, what they mean and how they work.

The most important option is the private key used for the APKs. At this time you can choose to upload the private key that Google will use for signing the APK, you can choose to let Google generate a new private key, or choose to use the same key as in another App that you have previously submitted.

Pay attention to the option you make in this step, as you cannot change it latter after submitting your App to Google Play.

One of the things you need to be aware of, is that if you let Google generate the private key to use, you will never have access to that key, and you will not be able to sign APKs yourself with the same key.

In case you need to distribute your App outside Google Play, either in other stores or for sideloading, if you choose to let Google generate the private key you will need to sign your APKs with a different key than the one that is being used in Google Play.

When you generate an AAB file in Kalipso you will also be asked for a signing key for the App Bundle file.

Don’t confuse this key with the APK private key.

This is a different signing key, that will be used for signing the App Bundle. Google will check this key when you submit your App Bundles to Google Play to validate that the file being submitted was really created by you, and not someone else trying to impersonate you.

Then before releasing your App to Google Play, Google will generate the APKs and sign them with the private key mentioned before.

When you try to make your first App Bundle submission, you will be requested with the App Bundle Upload Key Certificate.

In Kalipso, in the same screen where you configure the App Bundle generation, there is an option to export this certificate, so you can upload it to Google Play in your App submission.

You can read more information about Google Play App Signing here:

Use Play App Signing | Play Console Help (

What changes if I am not using Google Play for my Android Apps distribution?

In this case nothing changes. Kalipso will continue to generate the APKs without any change.

The new Android App Bundle format is only necessary for submitting Apps to Google Play.

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