This is a bot for adding camera and scanner categories to image files on Wikimedia Commons. It's run by User:BotAdventures.
It's written in Go and uses go-mwclient to interface with the MediaWiki action API.
The code is nothing special; most of the work is found in the mapping file from Exif fields to Commons categories (catmapping). The first two fields are the device manufacturer and model from Exif. The third field is the Commons category, where "Category:Taken with " is to be prepended in most cases.
Since I doubt that anybody else will want to run this bot, I haven't included much more in the way of documentation.
This package is freely licensed using the MIT License; see file LICENSE for details. I also release the catmapping file to the public domain (in case it's even copyrightable) using Creative Commons Zero.