Hey, thanks for the requests. I was originally planning on adding rule34.paheal.net, but they don't have a public API so I opted for rule34.xxx instead. The only other option is web-scraping--which Zenith Grabber doesn't support.
I don't personally see an uninstaller as being required since the program is 99.99% portable. If you want to remove *everything* (which only saves you a few kb of storage), you can delete the external data folder located at:
C:\Users\USERNAME\AppData\Local\stoozey_\GRABBER-ZENITH