Postman - The Collaboration Platform for API Development
Firebase - Firebase is a cloud service designed to power real-time, collaborative applications for mobile and web.
Amazon API Gateway - Create, publish, maintain, monitor, and secure APIs at any scale
restdb.io - restdb.io lets you create databases and REST APIs quickly. Development databases are free. Powerful web-based and mobile-friendly data management.
Apiary - Collaborative design, instant API mock, generated documentation, integrated code samples, debugging and automated testing
RemoteStorage - An open protocol for per-user storage OWN YOUR DATA