Files.com operates three types of SFTP integrations.
Files.com itself can operate as an inbound SFTP server, allowing you and your users to connect to your Files.com account via SFTP. This allows you to use SFTP to access any portion of your Files.com account, even folders that are syncing to other providers, such as Dropbox, Box, Amazon S3, etc.
Secondly, you can Mount an external SFTP site directly into Files.com as a folder. Files.com acts as an SFTP Client in this context, making that SFTP site available via the Files.com web interface, API, SDKs, and even other inbound SFTP connections.
Third, you can configure a scheduled Sync, where Files.com will synchronize its copy of a folder or folders on a one-way or two-way basis with the external SFTP server.
This integration requires Files.com's Enterprise Connectivity Addon, which is included for free on the Premier or Enterprise plan.