I'm a solo developer in Japan.I build tools that make work easier and less manual — the kind that take a step you would otherwise do by hand and turn it into something you no longer have to think about. Right now that is Proofkit, a pre-delivery checker for people who write in browser editors, and Markdown & Mermaid for Confluence, which is close to release.
I like tools that do one job, say plainly what they don't do, and can't damage the work you put into them. I'd rather ship something narrow that you can trust than something broad that you have to check behind.