You can check it out here: https://sightreading.training/
It's opensource: https://github.com/leafo/sightreading.training
It's very WIP, but I've used it a lot and I've definitely got a lot faster at reading notes. There isn't a good way right now to read rhythm in it. I pretty much use it as an experimental area for me to test new ideas to practice stuff, so there are a lot of little tools in there