I'm using Vizicities to visualise 3d building data on a map. Vizicities uses Mapzen vector tiles:
http://tile.mapzen.com/mapzen/vector/v1/buildings/{z}/{x}/{y}.topojson?api_key=[key]
With Mapzen closing, I've been looking for alternatives, like Tangram, but it seems Tangram is also relying on Mapzen data.
Is there any alternative that provides vector tile building data in a topojson format that might replace Mapzen?