There's also the `crypt` remote for rclone: https://rclone.org/crypt/
Rclone works fine, but the main difference to Cryptomator is that their mobile apps integrate well into the phone filesystems, essentially allowing you to modify the contents of an encrypted vault from mobile, desktop or wherever.
It’s basically cloud storage (works on local drives as well), but fully source encrypted.
It works transparently, and has clients for Mac/Windows as well as iOS/Android.
It's also open source, and "free" (IIRC there's a one time fee for the mobile client).
https://cryptomator.org/