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Pro Free and open source
FileZilla is free open-source software distributed under the terms of the GNU General Public License free of charge. Basically this means that everyone, including corporate entities, can use FileZilla, including but not limited to private, educational and commercial use.
Pro Suppots FTP and FTPS
FileZilla Server is a server that supports FTP and FTP over SSL/TLS which provides secure encrypted connections to the server.
In addition to Windows, FileZilla client is available for Unix, OSX and Linux.