Software Engineer II - Custom Objects

Klaviyo • Boston, MA

1d

About The Position

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 careers.klaviyo.com to see how we empower creators to own their own destiny.
Software Engineer II – Custom Objects Platform
Background
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: Profiles, Events, and Objects.
The Custom Objects team 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.
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.
How You’ll Make an Impact
Custom Objects unlock how customers represent their business inside Klaviyo.
In this role, you’ll:
Build systems that support customer-defined schemas and flexible data models
Enable other teams (Flows, Segmentation, Analytics, AI) to safely rely on object data
Work on platform primitives that must balance flexibility, correctness, performance, and cost
Contribute to a core data surface that directly impacts customer experience and product velocity

Requirements

• 3–6 years of professional software engineering experience
• Experience building backend systems in a production environment
• Strong fundamentals in data structures, algorithms, and system design
• Experience working with databases or data storage systems (relational or distributed)
• Ability to reason about correctness, tradeoffs, and edge cases in stateful systems
• Strong communication skills and comfort working with cross-functional partners

Nice To Haves

• Experience with schema-driven or user-defined data models
• Familiarity with distributed systems and high-throughput services
• Experience working with Python or similar backend languages
• Exposure to cloud infrastructure (AWS preferred)
• Experience supporting both online and analytical workloads

Responsibilities

• Design, build, and maintain services that power the Custom Objects platform
• Implement APIs and data pipelines for creating, updating, and querying custom object data
• Work with evolving schemas while maintaining backwards compatibility and data integrity
• Collaborate with Product, Events, Profiles, and Analytics teams to integrate custom objects into the broader platform
• Debug and improve performance of data-heavy systems operating at scale
• Participate in code reviews, design discussions, and on-call rotations
• Contribute to improving operational excellence through better observability and tooling

What This Job Offers

• Job Type: Full-time
• Career Level: Mid Level
• Education Level: No Education Listed