How to backup Android app's data without root

On Android, apps may have 3 pieces of data stored in different locations:

  1. Internal data under /data/data folder.
  2. External data under /sdcard/Android/data folder.
  3. OBB extension data under /sdcard/Android/obb
On Android 10 and below, both data #2 and #3 can be backed-up without any particular permission, but storage permissions.
On Android 11 and above, #2 and #3 requires special access permissions which can be granted from backup's dialog, activating external data (or from app's explorer by navigating to those locations).
Concerning #1 (internal data), without root, only the Backup Manager Service can backup/restore data on behalf of another and the guide below explains how to do so:

Requirements:

  1. Install either 3C Toolbox or 3C App Manager from Play Store.
  2. Requires a PC either running Windows, Linux or MacOS.
  3. Configure 3C Companion as detailed here: https://3c71.com/3cc
Constraints for internal data to be actually backed-up:
  1. it is mandatory that the app being backed-up is not stopped, otherwise Android will not allow backup.
  2. Some apps may be marked with a , in which case the developpers have decided not to allow internal data backup at all!
Steps:
  1. Start 3C Toolbox and go to App's Manager screen, or 3C App Manager.
  2. Select an app in Apps tab, and tap manage / backup.
  3. Enable internal data backup, the app will ask to enable an accessibility service that will help enter the backup password for you and quickly start backing-up data.
    1. If you don't enable that service the OS will ask you a password for both backing-up or restoring data, simply enter 3C for the password, otherwise the backup/restore will fail.
NB: It's possible the accessibility service gets disabled upon app updates (or if you force-stop the app), thanks to odd Play Store behavior force-stopping apps during update.
So you'll be requested to enable it again, unless you ask not to be asked again ;)