It is written in Python (Flask) with a simple interface.
Licensed under GNU Affero General Public License version 3.
Easy to deploy but you can also use the official instance.
deleted by creator
Oops, I made a mistake. You found the good URL. Thank you for your comment.
I just edited the original post to fix the link.
I tested the service with up to 400 users. On my own account I am following 122 feeds (with 285622 articles). But the goal is not necessary to have thousands of users on one instance. (it cost me a bit f money and registration are still free).
Overlaps somewhat with /c/floss_replacement and /c/privacy; crossposts welcome