Twilio is described as 'Web-service API that lets you use your existing web languages and skills to build voice and SMS applications. We focus on building a simple, powerful, pay-as-you-go communications platform so that you can focus on what you do best' and is an website in the social & communications category. There are more than 100 alternatives to Twilio, not only websites but also apps for a variety of platforms, including SaaS, Android, iPhone and Windows apps. The best Twilio alternative is UniStack. It's not free, so if you're looking for a free alternative, you could try Wazo or Fonoster. Other great sites and apps similar to Twilio are Dexatel, Smarter Contact, Lead Sherpa and Textmagic.