Filen is described as 'Cutting-edge cloud storage provider that offers client-side, end-to-end, zero-knowledge encryption. Headquartered and operated entirely in Germany, Filen is at the forefront of combining comprehensive features with uncompromising privacy and security' and is a very popular Cloud Storage service in the backup & sync category. There are more than 50 alternatives to Filen for a variety of platforms, including Web-based, Android, iPhone, Windows and iPad apps. The best Filen alternative is Nextcloud, which is both free and Open Source. Other great apps like Filen are Dropbox, Google Drive, MEGA and Proton Drive.
No end-to-end encryption is applied to the files.