Ask HN: Those making $500+/month on side projects in 2018 – Show and tell

Simple website for sending reminders. It didn't make any money for 4 years until I added commonly-requested features (templates, recurring reminders, and variables for recipient names). Now I have about 60 paying customers and it makes about $600 per month after all expenses paid. It's been running essentially autonomously for the past five months.

The iOS app is still difficult to use. I'm slowly rebuilding it. I'd say the main claim to fame at this point is if you Google "text message reminders" it's the first or second result.

There are probably lots of HN users who have really nifty side projects but won't disclose it for more or less the reasons you cite.

A site I built to teach myself bodyweight fitness (from a routine I found on reddit) -- grew a userbase and built up more detailed tracking, configuration, and usability.

The MRR is a bit hard to calculate right now (since I charge annually), but somewhere in the $500 - $1000 range.

Edit: This app grew from feelings of being stuck / burned out / almost depressed that can come from being in front of the computer too much. I was trying to build another startup out of college from my parents' house, and was having little progress or social interaction. There's been a number of threads about depression on HN recently, I felt the same. I realized I needed to be able to work out, but had no good gym accessible at the time, thus this little project was born (and went on to be more successful than the app I was initially trying to work on).