Top Alternatives to WebDrive

Duplicati is a backup tool, not a file sync tool.

Transmit is an FTP client for OS X. Developed by Panic, Transmit is shareware.

SyncBack is software which allows backing up and synchronizing files to the same or different drives, to different media (CD, DVD, Flash, zip), or to a remote server.

GoodSync is a backup and file synchronization program. It is used for synchronizing files between two directories.

RaiDrive is a cloud file manager that supports Google Drive, Box, etc

Insync is the most powerful Google drive client ever built. Windows, Mac, Linux, multiple account and external drive support, document conversion, etc.

odrive is a Universal sync client to unify, sync, share, and encrypt all your files in Amazon Cloud Drive, Dropbox, Google Drive, OneDrive, Box, S3, WebDAV, FTP, etc.

Gladinet is an on-premises, enterprise file synchronization and sharing (EFSS) platform.

ExpanDrive is a distributed file system client for Mac OS X and Microsoft Windows that facilitates mapping of local volume to many different types of Cloud Storage.

NetDrive is a drive mapping utility based on WebDrive technology.

CloudMounter is a reliable system utility that allows mounting different cloud storages and web servers to your Mac as local disks.

rclone is rsync for cloud storage.

SSHFS (SSH Filesystem) is a filesystem client to mount and interact with directories and files located on a remote server or workstation over a normal ssh connection.

win-sshfs is a small application designed as an SSH (SFTP) filesystem.

SFTP Net Drive helps you map remote drives as local drives.

AnyClient is a platform independent file transfer client supporting all major file transfer protocols including FTP/S, SFTP, WebDAV/S, Amazon S3 and AFTP.