Principal Engineer, Enterprise Scalability (Remote - East Coast Only)

At Klaviyo, we value the unique backgrounds, experiences and perspectives each Klaviyo (we call ourselves Klaviyos) brings to our workplace each and every day. We believe everyone deserves a fair shot at success and appreciate the experiences each person brings beyond the traditional job requirements. If you’re a close but not exact match with the description, we hope you’ll still consider applying. Want to learn more about life at Klaviyo? Visit klaviyo.com/careers to see how we empower creators to own their own destiny. At Klaviyo, we help businesses build stronger relationships with their customers. As our customers grow, our platform needs to support greater data volumes, more demanding workloads, and increasingly complex operations—with the performance and reliability they depend on. Engineering at this scale takes technical depth, sound judgment, and close collaboration. You’ll work across teams to solve challenging problems, turn architectural improvements into production results, and help build a platform ready for our largest customers. Your Impact We are seeking a senior technical leader to own Klaviyo’s approach to enterprise scalability, performance, reliability, and multi-region readiness. Reporting to a VP of Engineering, you will be a senior individual contributor with no direct reports. You will lead through technical expertise, hands-on engineering, and influence, partnering across teams to deliver improvements that matter to our customers. You will identify and remove major bottlenecks, drive platform-wide architectural changes, and establish clear measures of readiness for our largest tenants and most demanding workloads. Your work will span system design, profiling, implementation, and production rollout. You will also help teams adopt practical tools and repeatable patterns that make performance and reliability part of everyday engineering. This role suits an experienced engineer who can move between deep technical investigation and clear executive communication, make and defend architectural decisions, and build alignment across teams. Reports to: VP of Engineering Direct reports: None What You’ll Do • Define what scale readiness means. Establish measurable targets for latency, throughput, error rates, and capacity. Build a shared scorecard and align teams on service-level objectives, error budgets, and performance expectations for critical enterprise workloads. • Remove the bottlenecks that matter most. Use production data, profiling, and reproducible benchmarks to identify constraints. Partner with service owners to implement fixes and verify improvements under representative workloads. • Drive architectural change. Design and implement sharding, partitioning, caching, back-pressure, and workload isolation strategies. Advance multi-region readiness and build safe paths for high-volume data migrations. • Make scale engineering repeatable. Create lightweight benchmarks, profiling harnesses, and test environments that teams can use independently. Pair with engineers to turn successful fixes into reusable patterns. • Build readiness into delivery. Lead scalability reviews and establish clear, proportionate release gates that surface risks early and help teams ship confidently. • Turn incidents into lasting improvements. Lead technical deep dives, identify systemic causes, and work with teams to deliver and validate fixes that reduce recurring incidents. • Apply AI where it improves outcomes. Use AI-assisted profiling, workload modeling, synthetic traffic, anomaly detection, and guided runbooks to improve investigation and response. Establish explicit guardrails, evaluate results, and measure operational impact. • Connect engineering decisions to customer needs. Communicate priorities, tradeoffs,