Firebase Cloud Messaging (FCM) is a free messaging solution that lets you send web push notifications to your mobile app users. Firebase serves as a module between your server and the devices that will be receiving the push notifications that you create. Your server informs Firebase that a notification has to be sent. Then Firebase does the work behind the scenes to get the notification published.
Follow the below mentioned steps to use FCM:
Please note that you won’t be charged unless you manually upgrade to a paid account. You will get $300 to spend on Google Cloud Platform over the next 12 months.