Twilio - Brings voice and messaging to your web and mobile applications.
SendSMSnow - SendSMSnow is one of the best services over the internet that lets the users to send free SMS in any part of the world in addition to India.
Nexmo - Nexmo is a simple two way SMS API with global reach and wholesale rates
AFreeSMS - AFreeSMS is a free web-based service that allows you to send unlimited free SMS messages online, no need to register, just type your message and send unlimited SMS to anywhere around the world for free.
Clockwork SMS - Clockwork is an Easy Text Message API. An SMS API for Developers. Build powerful apps and include SMS. Signup is free, Try it now.
FreeSMS8 - FreeSMS8 is one of the best SMS sending websites that allow the Indian phone users to send free SMS to any mobile network operating in India.