GraphCMS is a CaaS (Content as a Service) provider based on GraphQL. It has been a GraphQL native since the very beginning and is currently the most popular GraphQL capable CaaS.
GraphCMS is a fresh startup with a plan to provide content feeds using the general purpose API Language known as GraphQL. This is without a doubt the tools' biggest strength as GraphQL has acquired some serious momentum in the course of 2016 and 2017. GraphCMS offers a free tier for hobbyists.
As opposed to open source tools, GraphCMS is a closed source product that locks the content in a specific service provider. This is an acceptable compromise for some organisations, but something that cannot be considered for professional publishing entities.