Parse or Firebase come to my mind... both have very generous starter plans. https://www.firebase.com/docs/rest/quickstart.html https://www.firebase.com/docs/re

Parse or Firebase come to my mind... both have very generous starter plans. https://www.firebase.com/docs/rest/quickstart.html https://www.firebase.com/docs/rest/quickstart.html https://www.parse.com/docs/rest/guide https://www.parse.com/docs/rest/guide