Do you guys know if there is any open-source project doing this kind of thing (UI for image labeling, NLP tagging, classification)? I think I've seen something like this before.
Here's one I wrote for my own use: https://github.com/jveitchmichaelis/deeplabel
It's not terribly feature complete (and it's not stable), but it's functional and pretty fast for basic bounding box annotation. My aim was to minimise clicks compared tools like labelimg, and also to have a database that I could work on with changes being stored immediately. Other tools seem to forget where you left off. I also didn't want a dependency on Python or the cloud.
It runs on a sqlite database, so presumably in a shared environment you could actually use it real-time collaboratively. I was doing some labelling for a project with my girlfriend and we simply took turns with the db and images a shared folder in Dropbox.