Never heard of mapzen until this post. Looks pretty cool. I am always skeptical of the lifetime of these service providers. I've seen quite a few come and go...and spent countless hours adopting replacement.
Pelias, the project powering our Search service is written entirely in node.js + Elasticsearch, to make it accessible to the largest number of developers, because JavaScript.
We also host an instance of Pelias to make the service accessible for those that can't/won't run their own.
More details [here](https://mapzen.com/projects/search).