&gt;they may store on servers behind the scene at least for speed and performance.<p>Yes, that&#x27;s why I think so. They easily loads all the messages and images in just few seconds even when my phone&#x27;s internet is too slow.<p>They won&#x27;t let you use the web app when you&#x27;re phone is disconnected, so there&#x27;s no way to confirm it.