Staff Software Engineer, Backend

Customer.io provides a platform for automated, personalized communication through email, push notifications, in-app messages, and SMS. The Staff Software Engineer, Backend will set the technical direction for distributed messaging systems, resolve high-stakes cross-team architecture problems, improve engineering practices, mentor senior engineers, and support system reliability.

Responsibilities:

• Shape the technical direction of our distributed messaging systems in Go — making the high-level architectural calls on mission-critical services where scale, cost, and reliability are all in tension
• Take on ambiguous, high-stakes problems that cross squad and function boundaries, and drive them to a decision when the right answer isn't obvious to anyone yet
• Build consensus on contested technical questions across teams, and communicate the tradeoffs clearly enough that senior leadership can act on them
• Raise the department's bar — set quality and design standards, mentor senior engineers, and turn what you know into frameworks and documentation other teams can use without you in the room
• Drive engineering process and tooling improvements that span multiple squads, not just your own
• Participate in an on-call rotation as required, supporting the reliability of the systems you build
• Interview and calibrate against our career ladder, giving honest, evidence-based assessments of candidates
• Use AI agents to make multi-file changes by scoping the work, writing the prompt, and verifying the output

Requirements:

• 10+ years building scalable, distributed systems in Go (or similar statically typed languages), including several as the person others turned to on architecture
• Depth across multiple systems or domains, not just one — you've been the recognized expert in more than one place
• A track record of designing for production reality: you quantify tradeoffs in throughput, cost, and reliability rather than picking a reasonable path and defending it
• Experience designing observability and recovery as first-class concerns — metrics, alerting, rollback, backpressure, checkpointing — not logging added afterward
• Comfort working in cloud-native environments (AWS, GCP), with relational databases (we use MySQL) and a real understanding of performance tradeoffs
• Evidence of making other engineers better: mentorship, technical writing, design review, standards that outlasted your involvement
• A bias for action over perfection, and the judgment to know which decisions are worth slowing down for