To elaborate on the warning-signs list, ones that are too-good-to-be-true, or where they don’t really seem to want third parties using their API, e.g. they didn’t document it, but somebody reverse-engineered it anyway.
Mega.nz error when check connection makes me wonder if “discourage” lasts until they find how to “stop”.
Amazon Cloud Drive - Why is it not supported? is a fairly hair-raising tale of impediments to getting started.
Do you / will you support Amazon Cloud Drive as a storage destination? speaks about “lukewarm” vendors.
About --> Libraries in the Duplicati GUI can help one look into how Duplicati gets to one’s particular storage.
Source duplicati/Duplicati/Library/Backend/ is another possible path.
Other ends:
Amazon shutting down CC’s Cloud Connection (Calibre Companion)
Discontinued Amazon Cloud Drive Support (Boxcryptor)
It’s too bad Amazon Cloud Drive took out rclone early, otherwise that could be helpful for migrating off ACD.
If anyone who’s migrated off of ACD has found a great tool, please post. I’m not thrilled by what I’ve seen…