We launched the CodeDrills recommender 6 years ago and since then it has been used to recommend problems for practice more than 10 million times! Unfortunately, over time, I got busy with other stuff and could not maintain it. Now I plan to open source the recommender so that it can be maintained by the community. For that I am looking for some volunteers from the competitive programming community.
CodeDrills has kindly agreed to continue to bear the hosting and other charges for the recommender.
More details here
Let me know if you are interested in the same.