Is there such an online service that accepts a POST / GET request and issues push notifications on its site for authorized users?

Question

Push technologies

Is there such an online service that accepts a POST / GET request and issues push notifications on its site for authorized users?
Please tell me the addresses of such services.

Answer 1

Firebase Cloud Messaging (FCM)

Answer 2

Vanga herself would have been in a stupor when trying to predict the author and subject of the content of the next notification.
Personally, would you subscribe to such "exciting" notifications on such a site?)))
PS Although if you take the eggs (which are being looked at) in your hand and turn them in profile, you will get something like a chat... But only for those who online, really... And with eggs)))