OneSignal - Customer engagement platform used by over 1 million developers and marketers; the fastest and most reliable way to send mobile and web push notifications, in-app messages, emails, and SMS.
Nexmo - Nexmo is a simple two way SMS API with global reach and wholesale rates
Firebase - Firebase is a cloud service designed to power real-time, collaborative applications for mobile and web.
MessageBird - Reach 7 billion phones in seconds via SMS, Chat & Voice. Try it for free and improve your communication.
Braze - Braze is an engagement platform that empowers growth by helping marketing teams to build customer loyalty through mobile, omni channel customer experiences.
Plivo - Plivo simplifies your customer engagement.