Twilio Flex - The programmable contact center platform 📱
LoopMessage - LoopMessage is a perfect macOS tool for personalized mass messaging via iMessage/SMS, WhatsApp, Facebook Messenger, Telegram, Viber, and Skype.
MessageBird Chat API - Connect with your customers through different messaging apps
SuperDMs - SuperDMs helps you grow your following by sending bulk DMs to your tweet responders.
MessageBird API on StdLib - Purchase numbers, send SMS and more with one line of code
Promote Route - A Better WhatsApp™ Experience