[artpar]

Try goms (https://github.com/artpar/goms)

These type of softwares are now increasingly known as BAAS - Backend as a service. You can also find other similar products on the github readme.

This is still in development, and I am using this as backend for two of my other projects. The goals are similar to what you have written, plus more.

[Norther]

This is nice! I hadn't heard of this category of services before today. I particularly like the idea of events in goms. Thank you.