It’s just a number that helps them give you questions that are about what you can handle.
This is from the site:
How do these ratings work?
Ratings measure your skill at each of the language activities we offer, and are a good estimate of your real-world language ability. Higher numbers are better, and the numbers tend to be between 1000 and 5000. If you’re familiar with chess ratings, then SuperNative work pretty similarly, except instead of comparing your ability against opponents, they measure you ability against individual questions.
I don’t think it’s really possible to say that a given number is equivalent to a given JLPT level. Because the reason why a given question is difficult isn’t always based on something the JLPT measures. Like, it could be that the person is shouting, and that never happens on the JLPT. On the recordings anyway.
I haven’t used the site in a long time, mostly because they tend to ask you about one specific word (in the Listen + Recall section anyway) and often it’s a long sentence with lots of small elements that aren’t being emphasized. My current rating is a little over 2700, though I had no trouble getting a few problems right just now. I just don’t find it particularly interesting, because I often know how to translate what the person said, but then they’ll want one specific particle or something.
My impression was that it never really goes down again, it keeps going up and up over time. Unless you really make a lot of mistakes but that seems unlikely since they are giving you level appropriate stuff usually.
My current scores, I haven’t been on the site for a year or so, I might give it another try today
I really like the site, the developer is amazing. It is the same guy that developed the Subadub browser extension that you can use for Netflix and https://voracious.app.
While I enjoy supernative, I somehow never managed to make a habit out of it. I think that is also why he started developing those other tools: making a habit out of this just works a little better if you can select your own content to use.