I think you mean without having to get a client. As in using what you already have that ships with Mac OS X. There is no way you are going to run FTP without an FTP client.
The one that ships with Mac OS is called "ftp". Run it from the terminal by typing "ftp". But many people cannot type commands so they get a third party FTP client. No configuration is required if you can get out on the 'net. Just run the client.