Cyberduck is an open source FTP, SFTP-client and also a WebDAV, Mosso Cloud Files and Amazon S3 browser for the Mac. It features an easy to use interface with quickly accessible bookmarks. The outline view of the browser allows to browse large folder structures efficiently and you can quickly preview files with Quick Look. To edit files, a seamless integration with several external editors makes it easy to change content quickly. An alternative: Filezilla.
