The whole backend stack is open source — check out https://github.com/mapbox/?query=vector https://github.com/mapbox/?query=vector (all things vector data) and

The whole backend stack is open source — check out https://github.com/mapbox/?query=vector https://github.com/mapbox/?query=vector (all things vector data) and https://github.com/mapbox/?query=fontnik https://github.com/mapbox/?query=fontnik (powers font processing for GL)