Elebase is a back end as a service with geospatial capabilities.
Elebase's fully managed platform provides a powerful API and a rich set of tools to help you build more elegant applications faster and more efficiently. Spend more time building custom features that solve customer problems, and less time designing and maintaining back-end systems.
Napkin Beta - Backend in the browser
restdb.io - restdb.io lets you create databases and REST APIs quickly. Development databases are free. Powerful web-based and mobile-friendly data management.
Horizon - Horizon is a realtime, open-source backend for JavaScript apps.
Firebase - Firebase is a cloud service designed to power real-time, collaborative applications for mobile and web.
Socket.io - Realtime application framework (Node.JS server)
RemoteStorage - An open protocol for per-user storage OWN YOUR DATA