Mapzen announced today that they were shutting down at the end of January 2018.

Our hosted APIs and all related support and services will turn off on February 1, 2018. You will not be charged for API usage in December/January. We know this is an inconvenience and have provided a migration guide to similar services for our developer community. Our goal is to help as much as possible to ensure continuity in the services that you have built with us.

Fortunately, the core products of Mapzen are built entirely on open software and data. As a result, there are options to run Mapzen services yourself or to switch to other service providers.

No reason was given for the move.