MultCloud - Multiple Cloud Storage Manager: Migrate, move, sync, copy, backup and transfer cloud files with MultCloud, which supports Dropbox, Box, Google Drive, Mega, OneDrive and FTP, etc.

FileZilla - FileZilla is an FTP, or file transfer protocol, client. It lets individuals transfer single files or batches to a web server. For many years, FTP was the standard for website design. Read more about FileZilla.

Koofr - Koofr offers safe EU based cloud storage with free storage space for life and options to connect multiple cloud accounts (Dropbox, Google Drive, OneDrive) and your personal storages.

PTFTP - Simplistic and intuitive explorer-like ftp client. Open source.

odrive - odrive aggregates all cloud storage. Access, sync, share, and encrypt everything in one place. Integrations to 20+ storage services, desktop sync, Linux support, placeholder files, zero-knowledge-encryption, web client, advanced sharing, and more!

WinSCP - WinSCP is an open source free SFTP client and FTP client for Windows.