Software Engineer II - Custom Objects

<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><h1><strong>Software Engineer II – Custom Objects Platform</strong></h1> <h2><strong>Background</strong></h2> <p>Klaviyo operates a real-time data platform built for massive scale, powering segmentation, automation, analytics, and personalization for hundreds of thousands of customers. At the core of this platform are three foundational data entities: <strong>Profiles</strong>, <strong>Events</strong>, and <strong>Objects</strong>.</p> <p>The <strong>Custom Objects team</strong> owns the platform that allows customers to define, store, and evolve their own domain-specific data models — enabling richer personalization, advanced segmentation, and flexible analytics beyond Klaviyo’s built-in data types.</p> <p>As a Software Engineer II on the Custom Objects team, you’ll help build and scale the systems that allow customers to safely model, query, and activate their custom data at scale.</p> <h2><strong>How You’ll Make an Impact</strong></h2> <p>Custom Objects unlock how customers represent <em>their</em> business inside Klaviyo.</p> <p>In this role, you’ll:</p> <ul> <li>Build systems that support <strong>customer-defined schemas</strong> and flexible data models</li> <li>Enable other teams (Flows, Segmentation, Analytics, AI) to safely rely on object data</li> <li>Work on platform primitives that must balance <strong>flexibility, correctness, performance, and cost</strong></li> <li>Contribute to a core data surface that directly impacts customer experience and product velocity</li> </ul> <h2><strong>What You Will Do</strong></h2> <ul> <li>Design, build, and maintain services that power the Custom Objects platform</li> <li>Implement APIs and data pipelines for creating, updating, and querying custom object data</li> <li>Work with evolving schemas while maintaining backwards compatibility and data integrity</li> <li>Collaborate with Product, Events, Profiles, and Analytics teams to integrate custom objects into the broader platform</li> <li>Debug and improve performance of data-heavy systems operating at scale</li> <li>Participate in code reviews, design discussions, and on-call rotations</li> <li>Contribute to improving operational excellence through better observability and tooling</li> </ul> <h2><strong>What We’re Looking For</strong></h2> <h3><strong>Required Qualifications</strong></h3> <ul> <li>3–6 years of professional software engineering experience</li> <li>Experience building backend systems in a production environment</li> <li>Strong fundamentals in data structures, algorithms, and system design</li> <li>Experience working with databases or data storage systems (relational or distributed)</li> <li>Ability to reason about correctness, tradeoffs, and edge cases in stateful systems</li> <li>Strong communication skills and comfort working with cross-functional partners</li> </ul> <h3><strong>Nice to Have</strong></h3> <ul> <li>Experience with schema-driven or user-defined data models</li> <li>Familiarity with distributed systems and high-throughput services</li> <li>Experi ... (truncated, view full listing at source)