Is Anyone Building “Foursquare But For Racism”?

I’m reading Nick Harkaway’s Gnomon right now, and one of the characters has just decided to create a new app that lets people tag their experiences on the street:

“So, like Foursquare,” my interviewer said, with the doubt of a young person looking at an old man in front of a computer.

“Exactly like that,” I said, “except that our users will record incidences of hate. We’ll be working initially to produce a live map—like a traffic congestion map—of more and less racist areas, safe routes home, institutionally racist police forces and local authorities, local populations. We’ll have a star rating system and so on.”

I immediately wondered if anyone is actually doing this. So far, all I’ve found is a recently launched app from South Africa called ZiRRA, which allows you to report incidents of racism but nothing more.

I’m surprised. The book was published three months ago, which seems like plenty of time for some hotshot Silicon Valley team to womp together a Foursquare clone in their off hours. What’s the holdup? Or does it already exist and I just don’t know how to find it?