So I'm still skeptical... because the branding, presence and everything is just way too professional to make me believe he's done this alone. I also believe that he's using multiple HN profiles to manipulate visibility (there are a number of profiles who's first comment is this on this post).

However, I do believe he is legit about his age.

Searching for his name, I found this old CodePen account: https://codepen.io/KingKabir/

There's a link in there to: http://www.main180.tk

That link is expired, but it showed up in this Quora from 2015: https://www.quora.com/Should-an-11-year-old-know-full-stack-...

Looking in the wayback machine, you can see what content his site used to have: https://web.archive.org/web/20151231214946/http://www.main18...

This lead me to this blog: https://180projectblog.wordpress.com/

It looks like he accomplished most of them? I didn't count, but the last entry on that site was in March 2016 (https://180projectblog.wordpress.com/2016/03/24/bubble/)

Moon was started in July 2016 (https://github.com/kbrsh/moon/commit/2e38db7571adf64c9192cfe...).

So while I'm still skeptical about his presence, I think it seems plausible that he is who he says he is, but that doesn't mean he's done it alone, etc, etc.