curl --request POST \
  --url https://push.platform.arb.inc/web-push/anonymous/subscribe \
  --header 'Content-Type: application/json' \
  --data '
{
  "subscription": {
    "endpoint": "https://fcm.googleapis.com/fcm/send/abc123def456",
    "keys": {
      "p256dh": "BKxMsq8lMmxKd_GFzCPJzCl8hQ3vVdYlQCL_bN8cLQhFk8z5pQ9hN1lMrT4xW2kP3sQ7",
      "auth": "8sFHd5kNuLVhw2pQ9xN1mT4"
    }
  },
  "vapidKey": "BNcRdreALRFXTkOOUHK1EtK2wtaz5Ry4YfYCA_0QTpQtUbVlUK3qW_HkkDQ3CskBSRU481zCtgwtR_jYDg9gNqk"
}
'

import requests

url = "https://push.platform.arb.inc/web-push/anonymous/subscribe"

payload = {
    "subscription": {
        "endpoint": "https://fcm.googleapis.com/fcm/send/abc123def456",
        "keys": {
            "p256dh": "BKxMsq8lMmxKd_GFzCPJzCl8hQ3vVdYlQCL_bN8cLQhFk8z5pQ9hN1lMrT4xW2kP3sQ7",
            "auth": "8sFHd5kNuLVhw2pQ9xN1mT4"
        }
    },
    "vapidKey": "BNcRdreALRFXTkOOUHK1EtK2wtaz5Ry4YfYCA_0QTpQtUbVlUK3qW_HkkDQ3CskBSRU481zCtgwtR_jYDg9gNqk"
}
headers = {"Content-Type": "application/json"}

response = requests.post(url, json=payload, headers=headers)

print(response.text)

const options = {
  method: 'POST',
  headers: {'Content-Type': 'application/json'},
  body: JSON.stringify({
    subscription: {
      endpoint: 'https://fcm.googleapis.com/fcm/send/abc123def456',
      keys: {
        p256dh: 'BKxMsq8lMmxKd_GFzCPJzCl8hQ3vVdYlQCL_bN8cLQhFk8z5pQ9hN1lMrT4xW2kP3sQ7',
        auth: '8sFHd5kNuLVhw2pQ9xN1mT4'
      }
    },
    vapidKey: 'BNcRdreALRFXTkOOUHK1EtK2wtaz5Ry4YfYCA_0QTpQtUbVlUK3qW_HkkDQ3CskBSRU481zCtgwtR_jYDg9gNqk'
  })
};

fetch('https://push.platform.arb.inc/web-push/anonymous/subscribe', options)
  .then(res => res.json())
  .then(res => console.log(res))
  .catch(err => console.error(err));

<?php

$curl = curl_init();

curl_setopt_array($curl, [
  CURLOPT_URL => "https://push.platform.arb.inc/web-push/anonymous/subscribe",
  CURLOPT_RETURNTRANSFER => true,
  CURLOPT_ENCODING => "",
  CURLOPT_MAXREDIRS => 10,
  CURLOPT_TIMEOUT => 30,
  CURLOPT_HTTP_VERSION => CURL_HTTP_VERSION_1_1,
  CURLOPT_CUSTOMREQUEST => "POST",
  CURLOPT_POSTFIELDS => json_encode([
    'subscription' => [
        'endpoint' => 'https://fcm.googleapis.com/fcm/send/abc123def456',
        'keys' => [
                'p256dh' => 'BKxMsq8lMmxKd_GFzCPJzCl8hQ3vVdYlQCL_bN8cLQhFk8z5pQ9hN1lMrT4xW2kP3sQ7',
                'auth' => '8sFHd5kNuLVhw2pQ9xN1mT4'
        ]
    ],
    'vapidKey' => 'BNcRdreALRFXTkOOUHK1EtK2wtaz5Ry4YfYCA_0QTpQtUbVlUK3qW_HkkDQ3CskBSRU481zCtgwtR_jYDg9gNqk'
  ]),
  CURLOPT_HTTPHEADER => [
    "Content-Type: application/json"
  ],
]);

$response = curl_exec($curl);
$err = curl_error($curl);

curl_close($curl);

if ($err) {
  echo "cURL Error #:" . $err;
} else {
  echo $response;
}

package main

import (
	"fmt"
	"strings"
	"net/http"
	"io"
)

func main() {

	url := "https://push.platform.arb.inc/web-push/anonymous/subscribe"

	payload := strings.NewReader("{\n  \"subscription\": {\n    \"endpoint\": \"https://fcm.googleapis.com/fcm/send/abc123def456\",\n    \"keys\": {\n      \"p256dh\": \"BKxMsq8lMmxKd_GFzCPJzCl8hQ3vVdYlQCL_bN8cLQhFk8z5pQ9hN1lMrT4xW2kP3sQ7\",\n      \"auth\": \"8sFHd5kNuLVhw2pQ9xN1mT4\"\n    }\n  },\n  \"vapidKey\": \"BNcRdreALRFXTkOOUHK1EtK2wtaz5Ry4YfYCA_0QTpQtUbVlUK3qW_HkkDQ3CskBSRU481zCtgwtR_jYDg9gNqk\"\n}")

	req, _ := http.NewRequest("POST", url, payload)

	req.Header.Add("Content-Type", "application/json")

	res, _ := http.DefaultClient.Do(req)

	defer res.Body.Close()
	body, _ := io.ReadAll(res.Body)

	fmt.Println(string(body))

}

HttpResponse<String> response = Unirest.post("https://push.platform.arb.inc/web-push/anonymous/subscribe")
  .header("Content-Type", "application/json")
  .body("{\n  \"subscription\": {\n    \"endpoint\": \"https://fcm.googleapis.com/fcm/send/abc123def456\",\n    \"keys\": {\n      \"p256dh\": \"BKxMsq8lMmxKd_GFzCPJzCl8hQ3vVdYlQCL_bN8cLQhFk8z5pQ9hN1lMrT4xW2kP3sQ7\",\n      \"auth\": \"8sFHd5kNuLVhw2pQ9xN1mT4\"\n    }\n  },\n  \"vapidKey\": \"BNcRdreALRFXTkOOUHK1EtK2wtaz5Ry4YfYCA_0QTpQtUbVlUK3qW_HkkDQ3CskBSRU481zCtgwtR_jYDg9gNqk\"\n}")
  .asString();

require 'uri'
require 'net/http'

url = URI("https://push.platform.arb.inc/web-push/anonymous/subscribe")

http = Net::HTTP.new(url.host, url.port)
http.use_ssl = true

request = Net::HTTP::Post.new(url)
request["Content-Type"] = 'application/json'
request.body = "{\n  \"subscription\": {\n    \"endpoint\": \"https://fcm.googleapis.com/fcm/send/abc123def456\",\n    \"keys\": {\n      \"p256dh\": \"BKxMsq8lMmxKd_GFzCPJzCl8hQ3vVdYlQCL_bN8cLQhFk8z5pQ9hN1lMrT4xW2kP3sQ7\",\n      \"auth\": \"8sFHd5kNuLVhw2pQ9xN1mT4\"\n    }\n  },\n  \"vapidKey\": \"BNcRdreALRFXTkOOUHK1EtK2wtaz5Ry4YfYCA_0QTpQtUbVlUK3qW_HkkDQ3CskBSRU481zCtgwtR_jYDg9gNqk\"\n}"

response = http.request(request)
puts response.read_body

{
  "subscriptionID": "3f8c7e4d-2a1b-4c9d-8e7f-6a5b4c3d2e1f"
}