I have been working on Audjust ( https://www.audjust.com/ ) on and off in my spare time. It's a service to manipulate (shorten/lengthen/loop) audio for video editors and music producers. I had a Show HN a while back that was well-received and kicked things off ( https://news.ycombinator.com/item?id=36480687 ). Since launching I have changed the name and added paid accounts which have brought in enough money to cover costs and make some profit!