FireFTP

FireFTP is a free and open source extension for Mozilla Firefox that allows you to transfer files between your computer and an FTP server. It is a powerful and easy-to-use extension that offers a number of features including:

- Transferring files from your computer to an FTP server and back

- Synchronizing directories between your computer and an FTP server

- SSL transfers for secure file transfers

- Setting up a proxy server to transfer files through a proxy server

- Setting up FTP commands to automate file transfers

- And more

It's a powerful, easy-to-use, and free extension that's available for all versions of Mozilla Firefox.