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Cyberduck is an open source FTP client.

cURL is a computer software project providing a library and command-line tool for transferring data using various protocols with URL syntax: supporting FTP, FTPS, SCP, SFTP, HTTP, HTTPS, TFTP, TELNET, DICT, LDAP, LDAPS and FILE. cUrl supports HTTPS certificates, HTTP POST, HTTP PUT, FTP uploading, kerberos, HTTP form based upload, proxies, cookies, user+password authentication, file transfer resume, http proxy tunneling and a busload of other useful tricks.

Commander One is dual-pane file manager for OS X created in Swift, which enables you to manage your files in the best possible way.

FireFTP is a free, secure, cross-platform FTP client for Mozilla Firefox which provides easy and intuitive access to FTP servers.

"Dual pane file manager and SFTP/FTP client for Mac OS XForkLift is designed to be the fastest, most powerful file manager for the Mac. Connect to FTP or SFTP servers, manage your Amazon S3 account or your mobile devices over Bluetooth. All these features are beautifully integrated into a sophisticated, yet easy to use Cocoa based interface. Dual-pane view will dramatically increase your productivity along with state-of-the-art features like live preview, spring loaded folders and any-to-any workflow. All this to be topped by tabs, to keep your workspace nice and clean." »

FileZilla Secure is a free FTP client that has all the features of the original FileZilla plus it encrypts your FTP passwords to help protect from hackers stealing them.

ExpanDrive is a Network file system client for Mac OS X and Microsoft Windows that facilitates mapping of local volume to any SFTP server the user can access. It also can connect to FTP, Amazon S3, RackSpace Cloud Files, OpenStack Swift Object Storage, DreamObjects, WebDAV, Dropbox, Google Drive and Box.com. When a server is mounted with ExpanDrive any program can read, write, and manage remote files (that is, files that only exist on the server) as if they were stored locally.

Yummy FTP Pro is an FTP/S + SFTP + WebDAV/S file transfer client which focuses on speed, reliability and productivity.

CloudMounter is a handy system utility that allows mounting cloud storage accounts and file-servers as additional drives on your Mac. The way it works is really easy: choose the service to mount with the help of a handy connections manager, login using your credentials and the mounted service or server will appear as an additional drive in Mac Finder.

Cute FTP is an utility for transferring files between your computer and a remote File Transfer Protocol (FTP) server anywhere on the Internet.

Nimble Commander for Mac OS X

Useful and reliable Mac FTP client. Viper FTP is a handy and powerful file manager for macOS, with a tremendous user interface that makes it effortless to use.

CloudBerry Explorer makes managing files in Amazon S3 storage EASY. By providing a user interface to Amazon S3 accounts, files, and buckets, CloudBerry lets you manage your files on cloud just as you would on your own local computer. PRO version offers FTP support.