Senior Software Engineer, Backend

About Customer.ioOver 8,000 companies – from scrappy startups to global brands – use our platform to send billions of emails, push notifications, in-app messages, and SMS every day. Customer.io powers... About Customer.io Over 8,000 companies - from scrappy startups to global brands - use our platform to send billions of emails, push notifications, in-app messages, and SMS every day. Customer.io powers automated communication that people actually want to receive. We help teams send smarter, more relevant messages using real-time behavioral data. Under the hood: Go, React, Ember and AI help us ship fast and scale with confidence. We’re looking for experienced backend engineers who care deeply about reliability, performance, and scalability. You’ll design, build, and evolve the systems that power communication at massive scale - while helping us push the boundaries of what great engineering can look like. What We Value Ownership You own problems end to end. You move fast, act like an owner, and thrive in ambiguity. You've led complex projects before, whether officially or not, and you're ready to do it again. Engineers with product taste You think like a user, not just an engineer. You care how your systems power real customer value - and how to make them better. A healthy skepticism for “the way things are done.” You bring rigor and creativity. Best practices matter - but never more than forward motion. What You’ll Do Design and build distributed systems in Go tha