I used a Bash script for a long time that would take my new bookmarks each month and download a copy of the page. It came from an idea presented on HN, I would ack-grep it for search.

Stores using it because I use several computers and two OS now, and the utility of it is pretty low for me.

You could make a donation to Archive.org and just a script to check for an "archive-this" tag in your bookmarks, then pass those pages to archive.org??

Do you still have the script perchance?

I'll have a look, you might find the one I based it off if you search here?

Zotero has been mentioned in this thread a few times, and it has this feature. The browser extension has both "with a snapshot" and "without" options (the snapshot being your local copy), and you can choose the default and also choose for each page if you want to.

(It does have some idiosyncrasies since it's supposed to be a citation manager originally, but once you get used to the workflow it gets out of the way and works really well.)