OpenTok supports multiple session configurations including simple one:one, multi-party in which all participants can stream video and audio to every other participant, and broadcast sessions in which a presenter can stream video and voice to a large number of subscribing audience members.
We have our demo site OpenTokRTC for users using OpenTok on a browser. For Android and iOS users, we have OpenTokRTC demo app for iOS and Android available in the Google Play Store and iTunes store. It implement multi-party chat feature along with text chat and archiving.
This demo app is open-source application and use best practice implementation. Please refer to Github repos: OpenTokRTC Github repo for web, OpenTokRTC Github repo for iOS, OpenTokRTC Github repo for Android