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Customer.io is seeking a Senior Software Engineer to own the email channel end-to-end. You'll work across the full stack—from infrastructure that reliably delivers billions of messages to the product surfaces customers use to build, send, and analyze campaigns.
Key responsibilities include:
- Build and evolve frontend experiences for campaign creation, preview, and analytics (editors, dashboards, configuration UIs)
- Design and scale backend systems handling high-volume message processing: queue management, retry logic, rate limiting, real-time event pipelines
- Develop automated systems that intelligently respond to feedback signals from external providers (classification, suppression, throttling, health scoring)
- Partner with domain experts to translate email knowledge into automated tooling
- Instrument and monitor channel health end-to-end: signal detection, anomaly alerting, observability
- Own problems completely—architecture, schema design, testing, deployment, monitoring
- Share knowledge through documentation, videos, and mentorship
- Leverage AI agents for multi-file code changes
Customer.io powers automated communication for 9,000+ companies, from startups to global brands, sending billions of emails, push notifications, in-app messages, and SMS daily. The platform uses Go, React, Ember, and AI to ship fast and scale reliably.
You don't need email experience—the company values engineers who love learning deep problem spaces. The ideal candidate owns problems end-to-end, thinks like a user (not just an engineer), moves fast, and brings both rigor and creativity to forward motion.
