tarsnap natively protects against inadvertent or malicious deletion or corruption — old tarsnap backups are immutablez The low-cost competitors (restic, borg, etc) seem to have this feature as an afterthought, and they make it surprisingly difficult.
(FWIW, S3 can be somewhat straightforwardly configured so that old data is effectively immutable. Google Cloud Storage’s similarly named versioning feature appears to be far weaker.)
Yep, S3 is reasonably easy to configure for immutability. I personally use restic to send (encrypted) blobs to https://www.borgbase.com which has append-only mode and monitoring to warn me if some backups didn't happen.
borgbase is another “little” service that I use and like just like tarsnap and to some extent rsync.net. And they also have an excellent gui app Vorta (it’s FOSS; borgbase dev is the maintainer).
(FWIW, S3 can be somewhat straightforwardly configured so that old data is effectively immutable. Google Cloud Storage’s similarly named versioning feature appears to be far weaker.)