I’m making around ~$600 MRR with Mentorbook.
It’s a tool that turns long-form content (PDFs, docs, YouTube videos) into structured, personalized courses based on how you want to learn.
I built it initially for myself — I consume a lot of content but struggled to turn it into a system I could actually finish and retain.
Early users came mostly from Twitter. Pricing is intentionally low ($9.9/mo), so it’s more of a slow, steady project than a high-growth one.
Still early, but I’ve learned a lot about what people are actually willing to pay for.