Firebase messaging, where to get Server Key?

Question

Firebase allows us to send notification messages via our own application by making POST request.

This tutorial, gives to us instructions how to make thi

Answer 1

There are two keys on firebase, the first one is in Settings (Tab General) and its call Web API Key.

The second one and in what you are interesting for is in Settings (Tab Cloud Messaging) its called Server key

Use the second one for push notifications from php.