We've developed a robust, dependable desktop application for backing up your entire ArcGIS Online org - feature layers, maps, apps, Survey123 packages, static files, and anything else you might have in there. Backups are local and you don't have to share your credentials with us. Backups can be sorted by item owner and filter by group, tag, owner, or folder(s), and you can add or remove delete protection for items included in the backup. Plus, you get a full item inventory with title, description, summary, number of views, tags, create/modify date, spatial reference, and owner.
We're a featured app on the ArcGIS Marketplace for July (listing), and we offer a free two-week trial.