FTP Droplet as the name indicates is a FTP tool for uploading files to your server. But unlike other tools this does not provide option to view all the files nor upload all the file types. This tool will allow your user to upload only one file at a time to a directory that you have specified. It does not mess up with file systems or permission issues. You can specify the type of files that can be uploaded.
The configuration file has the options to specify the server, user credentials and also the server path for uploading.
You can also set the allowed files and the max size of the files allowed. Once you create this settings, you can save the settings and the tool will create an encrypted file with the login credentials and also the path. You can pass this info to users who need to upload the files.
Since the config is encrypted, the users cannot modify any settings.