Principal Engineer, Enterprise Scalability

Klaviyo•Boston, MA

1d•$244,000 - $366,000

About The Position

Klaviyo is seeking a senior individual contributor to own its approach to enterprise scalability, performance, reliability, and multi-region readiness. Reporting to a VP of Engineering, this hands-on technical leader will partner across teams to deliver platform improvements for the company’s largest customers and most demanding workloads. The role has no direct reports and leads through technical expertise, engineering work, and organizational influence. The engineer will identify and remove major bottlenecks, drive platform-wide architectural changes, and establish measurable readiness standards. Work spans system design, profiling, implementation, and production rollout, as well as creating tools and repeatable practices that integrate performance and reliability into everyday engineering. The role requires moving between detailed technical investigation and executive communication, making and defending architectural decisions, and building alignment across teams. The position may require up to 10% travel, coordinated in advance. The U.S. base salary range is $244,000–$366,000. Total compensation may also include an annual cash bonus, equity, sign-on payments, and benefits, subject to eligibility.

Requirements

12+ years of relevant engineering experience, including a track record of scaling multi-tenant SaaS and removing significant bottlenecks with measurable production impact.
Hands-on expertise in performance engineering, capacity planning, sharding and partitioning, caching, back-pressure, tenant isolation, multi-region architectures, and large-scale migrations.
Ability to investigate unfamiliar systems, test hypotheses, write production code, and work with service owners to roll out changes safely.
Sound technical judgment, including the ability to use evidence to evaluate architectural tradeoffs and balance immediate constraints against broader platform investments.
Ability to align teams around shared outcomes, clarify ownership, and establish practical standards across organizational boundaries.
Clear communication of complex technical decisions and their business implications to engineering and executive audiences.
Practical experience applying AI tools or automation to engineering work, with the ability to assess their usefulness, limitations, and operational risks.

Nice To Haves

Curiosity about new AI approaches and discipline in validating their usefulness and impact.

Responsibilities

Define scale readiness targets for latency, throughput, error rates, and capacity; create a shared scorecard and align teams on service-level objectives, error budgets, and performance expectations for critical enterprise workloads.
Use production data, profiling, and reproducible benchmarks to identify constraints; partner with service owners to implement fixes and verify improvements under representative workloads.
Design and implement sharding, partitioning, caching, back-pressure, and workload isolation strategies; advance multi-region readiness and develop safe approaches to high-volume data migrations.
Create lightweight benchmarks, profiling harnesses, and test environments for teams; help engineers turn successful fixes into reusable patterns.
Lead scalability reviews and establish proportionate release gates that surface risks early and support confident delivery.
Lead technical incident deep dives, identify systemic causes, and work with teams to deliver and validate fixes that reduce recurring incidents.
Apply AI-assisted profiling, workload modeling, synthetic traffic, anomaly detection, and guided runbooks where they improve engineering investigation and response; establish guardrails and measure operational impact.
Communicate priorities, tradeoffs, and results to engineering and executive audiences, connecting technical investments to customer experience, enterprise growth, and operating efficiency.
Travel up to 10% for activities such as onboarding, client or partner work when applicable, team meetings, and industry events.