An SMS API is an application programming interface that allows businesses to send and receive text messages programmatically through an SMS gateway. An SMS gateway is a service that connects mobile networks with the internet, allowing businesses to send and receive SMS messages to and from mobile devices.SMS APIs are typically used by businesses to automate their messaging workflows, such as sending marketing messages, alerts, reminders, and notifications to customers or employees. With an SMS API, businesses can integrate text messaging functionality into their existing software systems, such as websites, mobile apps, or CRM platforms, and send messages at scale.