There's plenty of mostly old ftp clients software available available for GNU/Linux. You can use one but the simple truth is that you really don't need one; the simpler approach is to simply use any of the standard file-managers to access ftp sites.
ftp using standard file-managers
Thunar, Nemo, Dolpin and the rest of the file-managers support using
ftp://example.com/path/ links in the file navigation bar. In case you were wondering, other protocols like Samba work the same way;
smb://192.168.1.2/ will give you access to a local Samba server at that IP.
You can use user-accounts by entering
ftp: followed by
username:password followed by
@address. Full example:
Dedicated graphical ftp clients
A lot of the clients we used to recommend have not been updated in decades since ftp is an outdated protocol. kasablanca, ftpcube and iglooftp are no longer available in most distributions.
gftp is still hanging in there.. It is made using GTK2 and has all the features you expect from a fully featured ftp client. The interface is old school and simple, but not very user-friendly. gftp supports bookmarking of sites, logging, ssl and bandwith limiting. The bookmark editor is, like most of the other features, quite hard to use. By hard I mean that doing common tasks requires too much effort. It's website is https://www.gftp.org/
Console / termianl ftp clients
The GNU Midnight Commander is a advanced terminal file-manger. It has built-in support for FTP and uses the same standard format for login into ftp sites as graphical file-managers:
All distributions have MC. It's homepage is at http://midnight-commander.org/
ftp is the ancient standard file transfer tool from netkit. This is a basic thing installed on all Linux systems. There is no good reason to use this as your regular ftp client. Starting it will give you a
ftp> prompt where you can
open ftp sites. There is really no need to use this at all unless you really love to type in ftp commands manually.
ncftp' is highly configurable and in short excellent ftp client. In addition to the ncftp program you get ncftpput, ncftpget and ncftpbatch. These can with ease be used in scripts (and cron jobs). ncftp has more than all the features you will ever need in a ftp client. It's a great choice.