Daily Loop
Daily check-in widget
I wanted my daily routine visible without opening anything, so I put it in a home screen widget. It turned out useful enough to hand to other people. In English, Korean and Japanese, on Google Play.
Tr4wl
File search
I work on a Mac and missed the instant filename search I had on Windows, so I wrote one. It looks in the places Spotlight never indexes. Paid, and sold directly rather than through the Mac App Store.
Neither of these started as a product. They were things I needed, and they still get fixed when I need them fixed.