I'm wenbin, the author of this blog post & I built Listen Notes. Thanks for bringing up this question :)

Yes, Listen Notes is making some money - not a lot, but enough to cover all the cost and bring in a bit profit as of today.

The basic idea is that Listen Notes should be free to 99% of users, while making some money from 1% of super users.

We run ads (obviously) on the website and we provide API: https://www.listennotes.com/api/pricing/ And I've been experimenting some paid features that are needed for PR/marketing/journalists to do their job, e.g., https://www.listennotes.com/datasets/

And today is special, because on Sep 16, 2017 (Exactly 2 years ago today), I started to work on Listen Notes full-time!