The author mentions needing a small storage service and paying for JSONStorage. In fact, when I've needed this sort of thing in the past, Google Sheets is an amazing tiny database for projects. It has pretty generous API rate limits and it's convenient to be able to manage your DB live in a spreadsheet. In fact, even levels.fyi got away with a Google Forms / Google Sheets backend for a long time[1].
1. https://www.levels.fyi/blog/scaling-to-millions-with-google-...