I have personally worked as a freelancer for a few years of my career and I have a close family member who is an attorney. When I was doing my work, I always kept track of my client hours manually and noticed others doing the same.
I looked online for time tracking tools and realized there are a bunch out there, but none of them really satisfied me. Some were too bloated (i.e. slow!) and others were too limited. I thought it would be a fun side project to create a lightweight tool to scratch this itch. One product I really love is BitWarden - it's in a crowded market of other password managers, but hits the sweetspot by being lightweight, easy, fast, cross-platform, and open source. My goal is to go for this same sweet spot in market for freelancer tools.