title: Firebase Cloud Messaging (FCM) - HTTP V1 API or Legacy HTTP API?
body: <p>Our goal is sending notifications to <strong>groups of devices</strong> from our backend, and only from server side is possible to know which device should receive the notification.</p>
  
  <p>We've done some attempts with AppCenter because we mostly work with Xamarin iOS/Android/Forms, but now we have the doubt that it's probably better to use directly Firebase API because wider and more powerful.</p>
  
  <p>I see that with new version of API (HTTP V1) is not possible to send a notification to a list of tokens, feature that was available in legacy API using <code>registration_ids</code> parameter (<a href="https://firebase.google.com/docs/cloud-messaging/send-message" rel="noreferrer">https://firebase.google.com/docs/cloud-messaging/send-message</a>).</p>
  
  <blockquote>
    <p>Device group name (legacy protocols only)</p>
  </blockquote>
  
  <p><strong>I cannot use topics</strong> because when it's time to send the communication is a server's responsibility to prepare the "mailing list" for notifications.</p>
  
  <p>I was thinking to use device group messaging (<a href="https://firebase.google.com/docs/cloud-messaging/android/device-group" rel="noreferrer">https://firebase.google.com/docs/cloud-messaging/android/device-group</a>) but these are part of the legacy api, and I'm not sure if it makes sense/it's possible to use them with new version of API.</p>
  
  <p>Is an option to send a batch of 100-200-500 push notifications each one to only one token? In theory there isn't a limit to notifications which is possible to send, but I'm worried that sending too many of them I could risk to be banned.</p>
  
  <p>Is it better to use legacy API? Also AppCenter (Microsoft) uses legacy API, it's evident because of how the setup works and because from AppCenter's console it's possible to send notifications to a list of tokens, feature unavailable on Firebase's console.</p>
  
  <p>Another person just asked something similar but the answer was to use topics (<a href="https://stackoverflow.com/questions/49188386/how-to-send-firebase-notification-for-all-user-at-a-time">How to send firebase notification for all user at a time?</a>). </p>