Chat by Stream - Build and ship in app messaging in a few hours
Qiscus - Engage your customers from your own apps and mainstream chat apps like Whatsapp, LINE, Facebook Messenger, Telegram, Email, Twitter, Instagram, etc. and centralize all chats into a single dashboard.
QuickBlox - Cloud communication and data backend.
WeChat API - WeChat API and SDK allow developers to access and integrate the functionality of WeChat with other applications.
MirrorFly - World's Most Scalable Voice, Video & Chat SDK for Small, Medium & Enterprises
Kait.ai - Connecting People With Brands