Have you tried it yourself? With only one very general home screen and a sign me up button, I’d hate to give any of my details without knowing what I would be getting in return or what I would be expected to pay (if anything) further down the road.
Edit: I read a little more about it on Reddit and decided to give it a try. Apparently the front page is so bare because the creators are not maintaining it any more, they’re just keeping it running. I tried an exercise where you’re played a very short clip from what I assume to be a broad selection of actual Japanese media, then you see the sentence you heard written down, and you need to fill in one missing word to test your understanding and recall. Looks fun and promising, at least if the difficulty increases, because the first few clips were incredibly easy even for my own limited listening abilities.
Edit2: The difficulty does increase, and I’m loving the variety and the immediate feedback. This is really good for some brief but focused listening practice. Thanks for the recommendation, @pocketcat!