So magicbell is a dropdown displayed with an API?
$99 /month for 2000 users?
I don't understand what problem is trying to solve your startup. To me it seems that you're trying to sell a library more than a service.
I'm very glad MagicBell is tackling this — I never want to build another notification system myself, I'd much rather pay them to solve this problem for me!
I am glad that something like magicbell exists.