FileManager is described as 'for CKEditor' and is an website in the File Management category. There are six alternatives to FileManager, not only websites but also apps for a variety of platforms, including Windows, Self-Hosted solutions, CKEditor and ASP.NET. The best alternative is Flmngr. It's not free, so if you're looking for a free alternative, you could try Media Manager or Roxy Fileman. Other great sites and apps similar to FileManager are CKFinder (Paid), FileUltimate (Paid) and Responsive Filemanager (Free, Open Source).
CKFinder is powerful and easy to use Ajax file manager for web browsers. Its simple interface makes it intuitive and quick to learn for all kinds of users, from advanced professionals to Internet beginners.
RESPONSIVE FileManager is a free open-source filemanager image manager stand-alone and plugin for TinyMCE 4. It's possible to select files, images and videos from a server folder and upload them from your computer.