Postscript - Like Mailchimp for SMS
EZ Texting - EZ Texting provides SMS marketing solutions to businesses of all sizes.
GetChat.App - Add WhatsApp chat to your website for free
SimpleTexting - SimpleTexting offers SMS and text marketing services for companies of all sizes.
WikiPro - All-in-one Business to Customer Communication
Textmagic - The all-in-one solution for all your business texting needs - marketing campaigns, two-way SMS chats, reminders, notifications, and internal staff communication.