Starting Jan 31, 2019 Box.com is deprecating WebDAV support
To add to the to-do list of joplin, or an issue on GitHub could be enough as a reminder
Just adding a vote for continued Box support. Box is the cloud services provider for my work, which makes it a safe/approved/convenient place to keep my work-related notes. I’m sure all of us using Box (and especially those of us for whom Box is the employer-approved vendor) would greatly appreciate it if Joplin could provide Box-specific support in the same way it currently provides Dropbox-specific support.
(And, for the record, I’m extremely irked with Box for dropping WebDAV support and have said as much in their forums. It’s not fair that you and other developers who support open standards should now feel the pressure to fix something that was never broken. Unfortunately, because I’m locked into Box through my work there’s not much I can do.)
I agree with the sentiment that box.com screwed up big time. Why would someone want to remove a working and proven technology? I have a few theories, but I’m gonna keep them to myself.
This is unacceptable and box.com will notice this eventually when they’ve lost lots of customers.
I’m not the developer of Joplin, but if I were, I’d give box support the boot.
There’s always the workaround to install a box.com client and use a file system sync target. That beeing said, I’m also sure that PRs are always welcome.
Dropping it would be fair, but it'd be sad for those of us who are locked into Box through workplace demands. Regarding the proposed workaround…
…this would sync between different desktop installations of Joplin, but I'm afraid it wouldn't help with syncing to mobile clients, since these appear to sync exclusively to the cloud via WebDAV.
Yes, you are right. I haven't thought about that.
Luckily for you guys, I'm not the developer. 
However, imagine that you wrote a piece of SW that uses proven technology and because of some imbecile it's now worthless. Would you waste hours (maybe days) of research and coding to get to a point where you already had been?
I’m not arguing with you. It is the case that the developer already supports an API solution for Dropbox, though, which is Box’s primary competitor. So the equivalent major use case is already supported.
And I'm not arguing with you. (I just had to vent a little.)
This is why I believe that Joplin will support Box via an API sooner or later...
It’s unfortunate they dropped support for webdav and unless someone makes a pull request it’s unlikely it will be supported again. Google Drive and OneDrive Business aren’t even currently supported and these two would have higher priority.
No worries. Thanks, by the way, for the desktop syncing suggestion. I may still use it, even if it will limit my notetaking on mobile.
Fair enough. One thought: Box still (at least for now) continues to support sftp and rsync tools. I wonder if either of those methods could work as a generalizable solution, rather than writing something specific to Box’s API.
Upon reflection, another salient difference between Box and Google Drive as examples is that Box has until now featured WebDAV support. Because of this Joplin has an existing user base syncing through Box. Google Drive has never natively supported WebDAV, and so I imagine there are no Joplin users who currently sync with GDrive.
OneDrive Business does have WebDAV functionality, so in that sense it’s already supported.