The web push service allows you to send notifications both to http and https sites.
Subscription Request on an https Site
When users enter an https site, they see the following request:
If a visitor wants to get notifications from you, they just need to click "Allow."
Subscription Request on an http Site
When users enter an http site, they see the following request:
Then, if a visitor clicks "Allow," they see a pop-up where they have to click "Allow" for a second time. For example:
It is also possible to customize the request window. Read more about this function here.