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.
Openfire - Openfire (formerly Wildfire) is a cross-platform instant messaging (IM) and groupchat server.
Kait.ai - Connecting People With Brands
Prosody - Prosody is a modern flexible communications server for Jabber/XMPP written in Lua.
WeChat API - WeChat API and SDK allow developers to access and integrate the functionality of WeChat with other applications.
Matrix.org - Matrix is an open standard for decentralized persistent communication over IP.