How to Edit a File in an External Editor

You can edit a file just as a local file by clicking the Edit toolbar button or by choosing File → Edit With. The file will be downloaded to a temporary directory and opened with the preferred editor. Set your preferred editor in Preferences. The file will be uploaded to the server every time you choose File → Save in the Editor application. The file is not changed on the server if you just close the document without saving it or if the content has not changed.

Which Editor for What Files

The default editor of a file is selected using the default application for a given file typeset. If the default application is not one of the supported editors, the editor chosen in the Preferences is used instead.

To edit file type associations choose File → Info for a given file type in the Finder.app.

Preferences

Select Always use default editor in Preferences → Editor if you always want to use the default editor set regardless of the file type.

Hidden Preferences

Disable Upload of Temporary File on Save

defaults write ch.sudo.cyberduck editor.upload.temporary false

Problems

No External Editor Available

macOS only

If the editor does not show up as a choice in File → Edit With (the only submenu item is No external editor available), you may have to rebuild the LaunchServicesdatabase of OS X using Terminal.app:

/System/Library/Frameworks/CoreServices.framework/Versions/A/Frameworks/LaunchServices.framework/Versions/A/Support/lsregister \ -kill -r -domain local -domain system -domain user