[Added later: proper backup with an app requires rooting; otherwise the phone's and Google's backup are probably the best that can be done to back up apps and their data. A NANDroid backup with TWRP/Orangefox backs
everything up. Titanium can restore individual apps and data from a NANDroid backup.]
I've looked at Swift Backup following the recommendation in a post here, though haven't (yet?) tried it. I've checked lots of reviews, and xda-developers. I'll post what I found out (I don't think backup is off-topic for a forum to do with beta-testing, apologies if I'm wasting bandwidth). There is also a useful FAQ on the SB Web site. The Play Store page or the SB FAQ (I forget) gives the reasons for requiring Google account login.
Reviews on Google Play are worth reading.
xda discussion of Titanium's shortcomings with current Androids, and replacement:
https://forum.xda-developers.com/t/farewell-to-titanium-backup-looking-for-alternative.3932814/ Swift Backup seems to be the best-favoured.
I made some lengthy notes for my purposes (I need a good backup); I'll post them here, without editing. A lot of this is pasted from discussions, particularly if in "quotes".
Earlier free versions only backed up one-by-one; from v3.5 batch backup is possible in free version. Must sign in with a Google account, but can then be used offline.
Note: possibly backups not stored in the cloud are restricted to the device being backed up, can't restore to another. Swift Backup is associated with a particular Google account. [Note for xiaomi.eu posting: I later found info on restoring to a different device, see further down]
Android is becoming more restrictive. In particular, all partitions except /data are mounted read-only when running Android, so system apps can't be deleted while running; a custom recovery can be used.
adb backup is no longer supported by Google, and is likely not to work properly.
Removable SD cards and OTG storage is not supported for several purposes; use the built-in "sdcard" and copy files.
Swift Backup folder locations are fixed, both locally and in the cloud, and can't be changed.
For external storage of backups, copy the 'SwiftBackup' folder. Restart the app to detect the copied-back backup. Android/data/org.swiftapps.swiftbackup/SwiftBackup
Multiple backups aren't supported (one extra "archived" backup can be stored).
A Swift Backup user ID is used to make the encryption key; user passwords are not supported. As an alternative, upload backup files to a personal cloud server (PC/NAS device) using the available cloud options in the app like, for example, WebDAV.
"some apps may have additional security or keystore based protection which make it easy to detect a factory reset or a change in device. There is no way to fix this. Regardless, most apps restore fine with Swift Backup."
"using official version, but it always fails autentification" ... "clear data of Google Play Store and retry."
"is it possible to back up app data on one phone and sync it on an another?" ... "you can copy 'SwiftBackup' from your device or you can sync your app backup to cloud on device 1 and then use it on device 2 by switching the cloud backup tag in the 'Cloud sync' tab. Must use the same Google account in the app on both the devices."
"Significantly worse than Titanium Backup and Lucky Patcher and Uret Patcher; they all offer much more extensive possibilities besides backing up apps."
(2018) "the lack of system app support is a problem, as things like Gboard or Gmail that are installed to the system partition can't be backed up. The APKs don't need to be backed up, just the data." ... "System apps are tricky and I think most users don't know stuff before messing up with system apps (Accidental uninstall of a critical app). But restoring only data could be a good idea - working on it for later version."
"option to delete specific app backups (even specific backup parts) is available. Go to Local/Cloud synced apps, tap an app item which will open the detail screen. You can backup/restore/delete backups here."
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Hi. Just had and upgrade from OnePlus 6t to OnePlus 7 pro. I was thinking, that it's gonna to be easy walk in the park using my old friend Titanium backup. Ow how I was wrong. I used "migrate system data" checkbox checked Every third user app...
forum.xda-developers.com
Titanium hanging restore problem: I disabled "Verify apps over USB" and it allowed my hanging restores to complete. HOWEVER, the apps in question then crashed every time I tried to open them.
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Did you take a look at logcat for details of the crash? I had similar issues; I needed to change permissions/ownership on a single directory (/sdcard?). I had to do this once, and then all subsequent restores have been working fine. it's quite easy to do with "adb logcat" and then just try to start the app.
The best thing I did was not to try to restore everything on the new phone, but just selectively restore apps that I missed from the old phone over time. apps like signal/whatapp need specialized restore processes anyway due to encryption, and the storage of data outside of the app data location.
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Titanium Backup often does not restore the APK properly, but I have had great success in restoring app data and I can always download and install the app from APKMonk, APKMirror F-Droid or my backup APK. Without GAPPS, the Titanium Backup PRO key will not work and the free app is too limiting, though using a licence file should work.
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The problem of apps with split APK's makes it harder to make your own backup APK, and if you can't find the full APK on a mirror, you can be in trouble. I have found a good solution using SAI (which doesn't back up app data;
https://play.google.com/store/apps/details?id=com.aefyr.sai&hl=en&gl=US ).
I backup the app with TiB (which, as you say, does a good job still with the app data). And I backup the APKs with SAI. Between the two, I can rollback/restore/etcetera.
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Looking for an open source solution to backup individual apps and their data? OAndBackupX is a handy Android app for the job. Check it out!
www.xda-developers.com
Neo Backup (formerly OAndBackupX) is a fork of the famous OAndBackup with the aim to bring OAndBackup to 202X and part of Neo Applications suite. For now the app is already fully rewritten, coming up would be making it robust and adding some...
forum.xda-developers.com
Another option: oandbackup is an open source backer-up which has been criticised as not having many features and not updated since March 2019. OAndBackupX is a fork with "a sleek, modern user interface, compatibility with newer Android versions, the ability to handle split APKs, support for in-app backup encryption, and many more improvements". (3 Oct 20; app continues to be maintained Mar 21)