gFTP: Linux’s Answer to the Mac’s Transmit
On my Mac, I use Transmit to transfer files using different protocols. Unfortunately, it is not free and the free alternatives are not at par with transmit. 
On Linux, I use gFTP. Like Transmit, gFTP also supports other protocols in addition to FTP. Linux.com's Chad Files provides a more descriptive take on transferring files using gFTP.
(image taken from the gFTP site)