Mapzen focuses on building open source mapping components for developers.
We design things that can be provided as a service, but don’t have to be—tools that developers at any level can easily set up and use themselves. We don’t want to lock users into proprietary platforms, relying on black boxes they can’t take apart. That’s why we work on individual components, modular building blocks that anyone can use for better maps. We build things so you can build things.
Relatively new (at least to me), the collection of projects so far makes me think it’s worth keeping an eye on the work that comes from these folks. There’s an open source geocoder, a 2-D and 3-D mapping engine, and a vector tile service, all on GitHub. Plus, check out this blueprint-style prototype: