I'll start! My project is called Alchemist Camp (https://alchemist.camp). I believe I've made more free screencasts for learning the Elixir language than anyone else online, but I also put some behind a paywall. It's a side project that I spend around 10 hours a week on.

I started putting screencasts on YouTube at the end of 2017 and started charging last summer. My revenue is somewhat erratic since a large percentage of my customers sign up on an annual plan, but it's been covering my rent since the end of last year. My goal is to hit a baseline $2k MRR within the next 6 months.

The biggest challenge right now is that I started a lot later than my main competitors did. As a result, my site simply isn't on a lot of the lists, many of which include badly out-dated resources that don't compile with current versions of Elixir. There are always ways to improve the product, but I've probably underperformed more on the marketing side.

Longer-term, the popularity of the Elixir language itself is also a major consideration.