Customer.io is a data-driven marketing automation platform designed for sending targeted messages based on how people interact with your business. Founded in 2012, Customer.io focuses on helping companies create personalized customer experiences through behavior-based communication.

The platform specializes in event-based messaging that triggers communications based on user actions (or inactions). Customer.io offers multi-channel messaging capabilities including email, push notifications, SMS, and in-app messaging, all orchestrated from a single interface.

Customer.io provides powerful segmentation tools, visual workflow builders, A/B testing, and advanced analytics that emphasize conversion tracking and campaign performance. Its flexible API and emphasis on developer-friendly features make it particularly suitable for technology companies and digital-first businesses.

The service has gained popularity among SaaS companies, mobile applications, and subscription-based businesses that need to deliver timely, relevant communications throughout the customer lifecycle. Customer.io's focus on behavioral data activation and its ability to integrate seamlessly with product analytics tools distinguishes it from traditional email service providers.