TapTalk.io - TapTalk.io is a complete in-app chat SDK and messaging API - Easy integration and customizeable.
SlickText - Slick Text provides businesses and organizations with an easy and affordable platform for text message marketing.
Lets Chat - Open source self-hosted chat app for small teams
SimpleTexting - SimpleTexting offers SMS and text marketing services for companies of all sizes.
MongooseIM platform - The massively-scalable XMPPJabber mobile messaging platform, for mobile and web, by Erlang Solutions
Textmagic - The all-in-one solution for all your business texting needs - marketing campaigns, two-way SMS chats, reminders, notifications, and internal staff communication.