FileZilla is free and works well. It is often updated and I have never had a problem. If you code and have a few bucks, check out CuteFTP, you can edit a file in code without transferring the file. Good Luck.
Filezilla is by far my favorite but if you have access to the server the website is hosted on you can install something like cPanel that has a code editor and FTP client built into it. This would allow you to FTP from any computer and edit your work from anywhere.