CrushFTP is a powerful file server well ahead of its time. Not only does it handle serving FTP, but it also does SFTP (SSH FTP), FTPS (FTP over SSL), HTTP, HTTPS, WebDAV, and WebDAV SSL. From that list you can see it is serious about security and encryption.

CrushFTP Professional a allows an unlimited number of concurrent connections.

Features

• The built in fully customizable WebInterface allows you to present a website to customers so they can easily upload files to you, or download files from you. It has support for drag and drop uploading on the website, as well as the ability to upload folders while zipping them on the fly. This saves time and bandwidth. You get real-time feedback on the upload progress, speeds, and estimated time remaining. The WebInterface allows searching for files, thumbnails of images, slideshows, and managing your CrushSync client.
• Easily setup emails to come to you when a user uploads a file. Did the user upload 50 files? Don't want 50 emails? Not a problem. CrushFTP will build one email with all 50 items listed in it... even if they used a client that logged in with 10 connections to do the uploads!
• CrushFTP is easy to configure. You can drag and drop folders on a user to grant them access to the folder. The user will then only be able to access that folder. Not like OS X where they can browse around outside their home folder.
• The plugin support for CrushFTP allows for a whole new set of expandable features. One example allows you to make users by "creating a folder". That's all. You create a folder with a specific name, and a user with that name can then login with access to only that folder. You can't get any easier than that.
• Scared about giving users access to your computer? You can "preview" what the user will see with the user manager. You can control the access to every file or folder so there is no confusion on what a user can or can't do. Once a user has logged in, you can monitor what they are doing with the CrushFTP interface. See which directories they access, what files they download, and upload.
• Free training videos showcasing various features of CrushFTP are available on CrushFTP's homepage. Additionally, should you have questions or concerns, you have email access to support who will respond to questions very quickly.