FreeNAS gets fairly close to this out of the box. My home server runs ZFS with RAIDZ2. By default, I think, there's a weekly cronjob to scrub the ZFS pool (integrity check everything, as I understand it), and then the results of that scrub are emailed to me.

I don't believe it has a web interface with historical checks, although I could be wrong. That said, it might be stored in a log file somewhere.

I also don't have an external service that would send me an email if it failed to run. That said, I would get an email if cronjobs had a mysterious error; otherwise, if the server itself was dead, my data would not be accessible on my home network, so I'd notice.

If the home server dies tragically, well, I hope Google Cloud Storage is doing similar integrity checks -- that's where my offsite backups are.

Integrity is harder because you have to sort of maintain a signature of every file on the side. What I do is to just have a script that reads all data. If some data is unreadable an exception will be thrown and a text message will be sent to me. And a confirmation email is sent otherwise.

In .net it's only a few lines of codes. Haven't thought of deadmansnitch but it's a good idea. Would just take one more line of code.

git-annex has fsck command that can test the data and rclone remote so you can use any configuration of "cloud" storages to hold the chunks.