Founded by Colin Nederkoorn in 2012, Customer.io was created to help businesses send smarter, behavior-based messages instead of generic marketing emails. Today, it is a powerful customer engagement platform that combines customer data, automation, AI, and multi-channel messaging—including email, SMS, push notifications, in-app messages, and WhatsApp—to deliver highly personalized customer journeys. Users appreciate its flexible workflow builder, advanced audience segmentation, deep integrations, and the ability to create targeted campaigns based on real customer actions, making it especially popular with SaaS companies and growing digital businesses. Customer.io also offers enterprise-grade security and analytics to improve campaign performance. Pricing starts at $100/month for the Essentials plan, $1,000/month for Premium, with Enterprise pricing available on request, and it also provides a 14-day free trial plus a pay-as-you-go Builder option for developers.