Domus is a new web app I built for researching house history: who lived in a building, who owned it, when it was built, and how its address changed. Genealogists and local historians can record what they find, always with a source, and everything they add becomes open data that anyone can use and extend. This post describes how the project came about, what the app does, and how it is built.

Or: why I started working on open-source web genealogy.