Mountain Duck lets you mount server and cloud storage as a local disk in the Finder.app on Mac and the File Explorer on Windows. Open remote files with any application and work like on a local volume.
Cyberduck is a libre server and cloud storage browser for Mac and Windows with support for FTP, SFTP, WebDAV, Amazon S3, OpenStack Swift, Backblaze B2, Microsoft Azure & OneDrive, Google Drive and Dropbox.
- also see Cryptomator
Free client-side encryption for your cloud files.
Open source software: No backdoors, no registration.