TapTalk.io - TapTalk.io is a complete in-app chat SDK and messaging API - Easy integration and customizeable.
Notix.co - NOTIX is an audience re-engagement service based on web and in-app push notifications that work for both desktop and mobile devices.
Lets Chat - Open source self-hosted chat app for small teams
Firebase - Firebase is a cloud service designed to power real-time, collaborative applications for mobile and web.
WeChat API - WeChat API and SDK allow developers to access and integrate the functionality of WeChat with other applications.
Appcelerator - Native apps, Mobile APIs, Real-time analytics, One Platform.