PHP code snippet for sending a Firebase Cloud Messaging (FCM) notification

php-fcm-send.php

<?php

$authorizationHeader = "Authorization: Bearer <YOUR_ACCESS_TOKEN>";

/*
Steps to get Authentication Bearer :
    1.Got to Google OAuth Playground: https://developers.google.com/oauthplayground
    2.In the "Input your own scopes" for FCM use this url: https://www.googleapis.com/auth/firebase.messaging
    3.Tap Authorize API.
    4.Pick correct user for authorisation and allow access.
    5.In the Step 2: Exchange authorization code for tokens tap Exchange authorisation code for tokens.
    6.Access token is your Bearer.
SOURCE: https://stackoverflow.com/a/62670409
*/

$data = [
    "message" => [
        "notification" => [
            "title" => "Hello from PHP",
            "body" => "Hi this is body"
        ],
        "token" => "<CLIENT_REGISTRATION_TOKEN>"
    ]
];

$jsonData = json_encode($data);

$ch = curl_init("https://fcm.googleapis.com/v1/projects/<PROJECT_ID>/messages:send");
curl_setopt($ch, CURLOPT_CUSTOMREQUEST, "POST");
curl_setopt($ch, CURLOPT_HTTPHEADER, [$authorizationHeader, "Content-Type: application/json"]);
curl_setopt($ch, CURLOPT_POSTFIELDS, $jsonData);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);

$response = curl_exec($ch);
curl_close($ch);

echo $response;