It likely uses the data published by RiRs. I wrote something similar that discusses where it sources the data and how to generate it. https://github.com/geoacum

It likely uses the data published by RiRs. I wrote something similar that discusses where it sources the data and how to generate it. https://github.com/geoacumen/geoacumen-country https://github.com/geoacumen/geoacumen-country I've been meaning to make automatic Github releases for it.