Senior Software Engineer, Asynchronous Processing

About this role

<div class="content-intro"><p><em>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 <a class="_ymio1r31 _ypr0glyw _zcxs1o36 _mizu194a _1ah3dkaa _ra3xnqa1 _128mdkaa _1cvmnqa1 _4davt94y _4bfu18uv _1hms8stv _ajmmnqa1 _vchhusvi _kqswh2mm _ect4ttxp _syaz13af _1a3b18uv _4fpr8stv _5goinqa1 _f8pj13af _9oik18uv _1bnxglyw _jf4cnqa1 _30l313af _1nrm18uv _c2waglyw _1iohnqa1 _9h8h12zz _10531ra0 _1ien1ra0 _n0fx1ra0 _1vhv17z1" href="http://klaviyo.com/careers" data-renderer-mark="true">klaviyo.com/careers</a>&nbsp;to see how we empower creators to own their own destiny.</em></p></div><p><strong>Team Overview:</strong></p> <p>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.</p> <p>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.</p> <p>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.</p> <p><strong>How You’ll Make an Impact:</strong></p> <p>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:</p> <ul> <li>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.</li> <li>Design, develop, and deliver software to dramatically improve the availability, scalability, latency, and efficiency of Klaviyo's asynchronous and queueing services.</li> <li>Design and develop systems and processes that enable highly available &amp; scalable systems, with a focus on asynchronous processing.</li> <li>Leverage technology such as Python, Golang, AWS, and Kubernetes to advance Klaviyo's platform, with a deep focus on Apache Pulsar, SQS, and Kafka.&nbsp;</li> <li>Champion best practices by actively collaborating with other teams in a culture that values technical design review.</li> <li>Mentor and pair with other Klaviyo engineers to build better software by focusing on performance, self-healing systems, configuration as code, and defensive programming.</li> <li>Participate in periodic on-call duties with a focus on solving issues when they are discovered, preventing recurrences and minimizing alert fatigue.</li> </ul> <h4><strong>Who You Are:</strong></h4> <ul> <li>You are passionate about building software effectively and for the long term, balancing technical quality, velocity, and business impact.</li> <li>BA or BS Degree in Computer Science, related field, or equivalent experience.</li> <li>You typically bring 6+ years of hands-on software development experience building and operating highly available, full-stack SaaS products at scale, or have demonstrated equivalent proficiency and impact.</li> <li>You are independently responsible for the full lifecycle of complex projects or features, including discovery, technical design, implementation, rollout, and ongoing maintenance. You provide clear technical direction for others involved.</li> <li>You own the operational health of the systems you build, including performance, reliability, and observability. You are comfortable defining and upholding SLOs, participating in on-call, and driving follow-through on incidents and RCAs.</li> <li>Familiarity with cloud infrastructure (AWS preferred), infrastructure-as-code (Terraform), and containerized environments (Kubernetes), including how to design services that run reliably at scale in those environments.</li> <li>Expertise and hands-on experience with asynchronous processing and queueing systems like SQS, Kafka, or Apache Pulsar.</li> <li>Ability to handle yourself and complex systems in outage situations and to drive failures to root cause analysis and prevention of future issues.</li> <li>You’ve already experimented with AI in work or personal projects, and you’re excited to dive in and learn fast. You’re hungry to responsibly explore new AI tools and workflows, fi