I had a free weekend and, a few days earlier, Y Combinator had visited my school and handed out cloud and API credits. I ended up with about $25k in credits and no real plan for what to use them on.

I didn’t want to build another small utility or demo app, so I started thinking about things I’m personally curious about. One thing that’s always bothered me about maps is how static they are. They’re good at showing where things are, but not when places actually come alive, quiet down, or shift over the course of a day.

So I decided to use the weekend and the credits to see if I could build something that made the time dimension visible. That experiment turned into a small project that aggregates real world activity signals and renders them as a time based heatmap so you can scrub through a day and watch how different parts of a city change.