Cyberduck

Cyberduck is an impressively powerful file transfer client that attempts to be a unique tool, capable of handling almost any popular kind of server there is, including FTP, SFTP, WebDAV, Amazon S3, Google Cloud Storage, Rackspace Cloud Files, Backblaze B2 and Google Drive.

Furthermore, it works with third-party providers using the S3 or the Openstack Swift APIs, and lets you connect to HP Cloud Object Storage, Internap, EVault LTS2, Oracle Storage Cloud Service and many others.

Despite these awesome capabilities, Cyberduck is neither costly nor complicated to use. On the contrary, it's open source, so anyone can use it for free and even access its source code, and it's also pretty easy to use, thanks to its neat, well-structured, self-explanatory interface.

There are still a lot of cool things about this amazing tool. To mention just a few, Cyberduck offers really fast FTP transfer speeds, lets you edit files with any editor of your choice, and helps you easily distribute your content on the cloud using acknowledged content delivery networks like Amazon CloudFront and Akamai. Furthermore, it comes with handy and convenient bookmarking capabilities, it allows using and browsing your Amazon S3-hosted content like it would be on one of your local disks, and it includes powerful SSH-related additional features that enhance its authentication and archiving functions.

As you can see, Cyberduck may look simple, but it's got immense power under its hood, and I'm sure many users will continue choosing it as their default file transfer tool, as it offers all the good reason for this choice.