The Enginio Data Storage is a secure, fully-managed cloud data storage service launched by Digia, the commercial entity behind Qt. Digia is planning for mainline Enginio support within Qt and to make it very easy to use their cloud storage service as a way of promoting their cloud over other Backend-as-a-Service (BaaS) solutions.
The Enginio Cloud Data Storage supports any type of files, a rest API interface and various other integration for web and desktop/mobile platforms, centralized management, etc. Pricing on Digia's cloud service is free if only needing 1GB of storage and 100K monthly I/O events. The entry-level package will set back developers $149 USD per month for 10GB of data storage and one million monthly I/O events. Other custom cloud (or private cloud) offerings are provided on an individual basis with Digia.
Digia is planning to mainline their Enginio library into the official Qt 5. release while available already is an option to use it with the Qt 5.2 online installer.
Digia's Enginio plans for Qt 5.3 were shared via this mailing list post. Additional information on the cloud service can be found at Engin.io.