Almost 100% of sales come from organic searches. Usually people would search for things like "Docker course" or "Flask course" and either find my course near the top of Google or they would search for some specific problem related to that content and come across a blog post I wrote on my main site which linked back to the course somewhere (usually).

Now the same thing happens, but there's 20x less sales per month.

I've posted almost 400 free videos on YouTube as well over the years, usually these videos go along with the blog post.

A few years back I also started a podcast and did 100 weekly episodes for 2 years. It didn't move the needle on course sales and it was on a topic that was quite related to app development and deployment which partially aligns with my courses. Most episodes barely got ~100 listens and it was 4.9 rated out of 5 on major podcast platforms, people emailed me saying it was their favorite show and it helped them so much and hope I never stop but the listener count never grew. I didn't have sponsors or ads but stopped the show because it took 1 full day a week to schedule + record + edit + publish a ~1-2 hour episode. It was super fun and I really enjoyed it but it was another "invest 100 days, make $0" thing which simply isn't sustainable.