Senior Software Engineer - Flows Platform

<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> to see how we empower creators to own their own destiny.</em></p></div><h3><strong>About the Role</strong></h3> <p>Klaviyo is looking for a Senior Software Engineer to join the <strong>Flows Platform</strong> team. In this role, you will help build and operate the core engine that powers all automated lifecycle programs at Klaviyo. You’ll play a critical part in delivering robust, high-scale backend solutions that process billions of events, send millions of messages, and ensure our customers’ automations run reliably and without delay.</p> <p>As a Senior Software Engineer, you’ll tackle complex challenges, explore multiple solutions, and weigh business and technical trade-offs to determine the best path forward. You’ll actively contribute to team discussions and help shape important technology decisions. You'll also be responsible for shipping well-designed, thoroughly tested solutions that prioritize reliability and performance.</p> <p>On the <strong>Flows Platform</strong> team, we focus on the core of Klaviyo’s automation engine, ensuring that hundreds of millions of actions per day are processed accurately and efficiently to power user workflows. Our work revolves around the core backend systems that determine who receives a message and when, handling complex logic for triggering, filtering, and scheduling at massive scale. We also manage the data stores and infrastructure that support these operations, ensuring reliability while we actively re-architect our stack to support the next generation of event-driven features.<br><br>We are responsible for:</p> <ul> <li>Core Execution Engine: The logic for flow triggering, evaluation (filtering/branching), and action execution. We ensure that every event is processed accurately and efficiently.</li> <li>Scheduling Orchestration: Managing time-based logic, delays, and the dispatching of millions of scheduled actions per day.</li> <li>High-Scale Infrastructure: Owning the execution data stores and pipelines that must run reliably at huge scale.</li> </ul> <p>Collaboration is key to what we do. We actively partner with engineering teams across the organization, giving us exposure to diverse parts of the product and opportunities to impact various projects. This keeps us engaged with a variety of challenges and solutions, as we’re always learning and evolving.</p> <p> </p> <h3><strong>What We’re Looking For</strong></h3> <ul> <li>6+ years of experience in a software engineering role with a focus on backend systems and high-volume data processing.</li> <li>Deep experience building robust services and APIs using Python and Django (or similar frameworks).</li> <li>Demonstrated experience designing large-scale systems, managing technical debt, and making high-level architectural decisions.</li> <li>Distributed systems knowledge and deep experience working with asynchronous task queues (e.g. Celery, RabbitMQ, Pulsar) and understanding the challenges of eventual consistency and distributed state.</li> <li>Expertise in relational databases (MySQL/Aurora) and high-scale NoSQL stores (Redis or DynamoDB).</li> ... (truncated, view full listing at source)