Senior Software Engineer - Asynchronous Processing

Location: Boston

This job is with Klaviyo, an inclusive employer and a member of my Gwork – the largest global platform for the LGBTQ+ business community. Please do not contact the recruiter directly.

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.

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Team Overview:

The mission of the Asynchronous Processing team is to design, build, and operate Klaviyo’s high-scale, event-driven backbone so that every product team can reliably move data through our systems with confidence, no matter the volume. By providing opinionated, self-service platforms for queueing and background processing–grounded in technologies like Golang, Python, Apache Pulsar, Kafka, SQS, AWS, and Kubernetes–we enable engineering teams to focus on customer impact while we ensure their workloads are fast, observable, cost-efficient, and resilient by default.

As a Senior Platform Engineer on the Asynchronous Processing team, you will architect, build, and operate the large-scale, event-driven backbone that powers Klaviyo, crafting paved-path primitives on top of Golang, Python, Apache Pulsar, Kafka, and SQS running in AWS and Kubernetes. You’ll design and evolve resilient, multi-tenant queueing and processing platforms that safely handle massive spikes in traffic, process millions of messages per second with low latency, and provide simple, self-service APIs and tooling that enable product teams to move fast and with confidence.

From core data models and routing patterns to observability, autoscaling, and failure isolation, you’ll own systems that must be rock solid at scale, partnering closely with engineers across the company to turn complex distributed-systems problems into intuitive, reliable building blocks.

This role is for senior engineers who love taming large-scale distributed systems and turning real-world asynchronous workloads into reliable, scalable platforms. You’ll work on highly visible infrastructure at the heart of Klaviyo’s event-driven backbone, directly shaping how thousands of Klaviyos build, ship, and operate products every day.

How You’ll Make an Impact:

The Asynchronous Processing team builds and operates Klaviyo’s high-scale, event-driven backbone that powers reliable, low-latency async workloads for every product team. As a Senior Platform Engineer on the Asynchronous Processing team, you will:

Build a deep understanding of engineering needs across the organization, guiding the design and development of appropriate platform primitives in queueing that align with the platform's vision and practically empower product teams.

Design, develop, and deliver software to dramatically improve the availability, scalability, latency, and efficiency of Klaviyo's asynchronous and queueing services.

Design and develop systems and processes that enable highly available & scalable systems, with a focus on asynchronous processing.

Leverage technology such as Python, Golang, AWS, and Kubernetes to advance Klaviyo's platform, with a deep focus on Apache Pulsar, SQS, and Kafka.

Champion best practices by actively collaborating with other teams in a culture that values technical design review.

Mentor and pair with other Klaviyo engineers to build better software by focusing on performance, self-healing systems, configuration as code, and defensive programming.

Participate in periodic on-call duties with a focus on solving issues when they are discovered, preventing recurrences and minimizing alert fatigue.

Who You Are:

You are passionate about building software effectively and for the long term, balancing technical quality, velocity, and business impact.

BA or BS Degree in Computer Science, related field, or equivalent experience.

You typically bring 6+ years of hands-on software development experience…