CarotDAV is a free and open-source backup and sync application that enables users to store, share, and access their files across multiple devices. It is a desktop client for Windows, Mac, and Linux, as well as a web interface for users to access their files from anywhere. It supports a variety of file types, including text documents, images, videos, and audio. CarotDAV also offers a secure, encrypted connection to its servers, ensuring the privacy of your data. With the built-in versioning and file sharing features, users can easily keep track of their file versions and share files with others. Additionally, CarotDAV supports integration with other applications and supports a variety of cloud storage services, including Dropbox, Google Drive, and OneDrive.
Bundleware The installer may contain adware. Be careful during installation: https://alternativeapp.info/discussions/applications/11718/be-careful-in-the-installation/
Filezilla no admite SkyDrive / DropBox / GoogleDrive / Box / SugarSync
Discontinued Last commit 3d05473 on September 3, 2015. See https://github.com/timshannon/freehold
Discontinued It appears that the service is no longer updated since 2012 and the iPhone app is no longer available. You can still register new accounts and the website seems to work.
Warning Be aware that installing FileZilla on your computer might install some packages / malware on your machine. See this thread in the FileZilla forum: https://forum.filezilla-project.org/viewtopic.php?f=2&t=48441