Is there a cloud DB with REST API and simple authentication?

Question

Database

I need a very simple thing: the ability to write to the database via REST from my mobile application.
I spent a lot of time searching and checking cloud databases, but so far I have not found a normal option.
I would be grateful if you could give me some advice from your experience.
I tried different options - AWS, Firebase, cloud.mail.ru, Elastic, restdb.io
The main criterion: ease of authentication in the database, best of all based on the API Key, and ease of use of the API itself.
Monsters (AWS, Firebase, mail.ru) have very sophisticated cloud services, and for a simple REST call, you need to write almost a separate application + I never saw the possibility of using the API Key.
Elastic is a good option in terms of authentication, but it has a very complex API. You need to dig almost the entire Internet to understand how to make a simple INSERT.
Restdb.io turned out to be the best option in terms of interface simplicity and usability. Connected very quickly.
But it turned out that the service is not as reliable as we would like (it happens that it lies down and does not rise for a long time).
If you know a good database option with simple authentication and REST API, I will be very grateful for your hint

Answer 1

A service with a REST API for only a database and with a previously unknown set of fields? I would like to see the psychos who would implement this as SAAS

Answer 2

Pick up GrapQL. Apollo or Prisma or graph.cool / . It couldn't be easier.