Twilio - Brings voice and messaging to your web and mobile applications.
Clearstream - Clearstream is a SMS marketing and online texting software.
Plivo - Plivo simplifies your customer engagement.
E-goi - Email Marketing companies, SMS Marketing, software email marketing.
Nexmo - Nexmo is a simple two way SMS API with global reach and wholesale rates
Maytapi - Serverless Whatsapp Api with Chat and Agent support.