List of free FTP stuff for developer👇🏽
If you're looking for all programming tools around FTP (not just free). Check this page List of FTP Programming Tools
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.
FileZilla - The free FTP solution for both client and server. Filezilla is open source software distributed free of charge.