A new Chrome App lets you access SFTP servers right from your Chrome OS devices.
Announced in a Google+ post by developer Yoichiro Tanaka, and shared by Googler François Beaufort, SFTP File System leverages the new File System Provider API to connect to SFTP servers right from Chrome OS.

The File System Provider API recently landed in the stable channel with Chrome OS 40 and gives developers the ability to integrate new virtual file systems into Chrome OS alongside the built-in Google Drive integration.
While the Chrome devs have been focused on bringing the likes of Amazon S3, WebDAV, and Dropbox support to Chrome OS, Tanaka’s Chrome App is a boon for anyone needing access to SFTP servers to upload assets or backups right from their Chromebooks.
Using SFTP File System
SFTP File System has a simple interface, with some very slick Material Design cues, that makes it easy to access your servers. Upon entering the correct credentials, your SFTP file system will be mounted and accessible from the built-in Files app.

From there you can add, delete, and modify files as per usual. If something is taking too long, Chrome OS will pop up a notification asking if you’d like to abort the operation – an excellent point of integration and a huge plus if you’re working off a spotty Wi-Fi connection.
And when you’re through, you can unmount your SFTP server by clicking the eject icon in the sidebar or right-clicking and hitting “Close”. You can also save your connections to the sidebar by pressing the “Keep” button in the app, though you’ll need to enter your password again.
Getting SFTP File System
SFTP File System is available right from the Chrome Web Store. It’ll only work on your Chromebooks, -bases, and -boxes as the File System Provider API is only available on Chrome OS.
- Source: François Beaufort via G+