Flow is an award-winning, beautiful, fast, and reliable FTP + SFTP client. With URL Copying, Droplets, a built-in editor, and QuickLook, it's no wonder why Flow is the go-to choice for those who want the best.
UNPARALLELED SPEED
A file-transfer client is only capable of being as good as its connections are. That's why we left nothing to chance: Flow is powered by ConnectionEngine, providing the most modern, efficient, and fast connections in the world. Engineered to take full advantage of multi-connection concurrency, nothing comes close to Flow's resilience, reliability, or speed.
COPY AND VIEW URLs
Copy or open the URLs to your remote files in a single click. Automatically copy URLs to the clipboard after uploading. Flow pioneered such URL-awareness, so no other app comes close to Flow's deep URL integration.
DROPLETS
A droplet is a mini-application that lets you upload files insanely fast — in literally zero clicks. Drop a file on a droplet, and boom. The file is uploaded without even opening Flow. A window showing the progress of the upload appears. When the upload is finished, the window disappears. The URL to the uploaded file can even be copied to your clipboard. Droplets in Flow are unmatched by any other app on the planet.
EDITING
Flow is the backbone for the daily work of thousands of web developers. Flow can edit files on your server in your favorite text editor, like TextMate, or with the built-in editor, replete with a web-preview of your code, tabs, syntax coloring, and even code completion. No matter what editor you use, when you hit "save", the updated file is instantly uploaded to the server.
QUICKLOOK
Designed exclusively for OS X, Flow has QuickLook just like the Finder. Whether you've got an image, HTML file, PDF, or Keynote presentation — anything — a tap on the spacebar is all it takes to preview your files without opening them.
Five Details 
Comments and Reviews
Flow is not your traditional (S)FTP client. I like the GUI and the built-in editor a lot. FileZilla for example, despite the 1,3 million features, in my view has a poor interface. Flow is simple but does the job.
I got Flow as part of a Mac Heist bundle. While I like the UI much better than Cyberduck, my previous file transfer client, I have found Flow to be a bit buggy. SCP transfers of more than 3 files can cause issues on a couple of servers I connect to. And there are a couple of small UI bugs that have annoyed me. In general it's a fine application, but I would stick with Cyberduck (or Transmit) for now.