Lead Software Engineer - Campaigns

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Location: Boston Hybrid (3 days/week in office)

The Campaigns Configuration team is building the foundation for how Klaviyo customers create, manage, schedule, and understand the performance of their marketing campaigns across channels. This team owns the core configuration and reporting experiences that power Klaviyo’s Campaigns product.

Campaigns are one of the most used parts of the Klaviyo application, relied on by hundreds of thousands of customers to send targeted messages (Email, SMS, Push Notifications, and more) that deepen their relationships with their own customers. By joining the Campaigns Configuration team, you will have a direct impact on over 170,000 brands that use Klaviyo every day.

The team owns an ambitious roadmap, including:

• A reimagined Campaigns experience built from the ground up
• A new Omnichannel Campaign experience allowing users to send campaigns on multiple channels
• Intelligent personalization and future channel expansion
• Refactoring Klaviyo’s system architecture through domain decomposition
• Re-architecting the Campaigns experience for performance, scalability, and reliability

As a Lead Software Engineer, you are the technical leader and primary interface between the Campaigns Configuration team and the broader engineering organization. You will:

• Provide technical oversight and direction across a portfolio of projects
• Shape and execute on the forward-looking architecture for multiple Campaigns domains
• Partner closely with the Engineering Manager, Product, and Design on strategy, planning, and execution
• Work through influence and delegation to help the team deliver reliably and at a high bar of quality

You’ll spend your time balancing hands‑on work (design docs, reviews, complex implementation) with guiding the team toward solid technical decisions, especially at our largest scales (including Black Friday / Cyber Monday, when we help customers send billions of messages).

• Lead technical direction for Campaigns Configuration
  • Provide technical oversight and direction for a portfolio of Campaigns projects, including new channels, personalization, and analytics.
  • Formulate and drive a forward‑looking technical vision that aligns with broader business and platform initiatives.
• Own architecture and domain evolution
  • Be responsible for the technical and architectural evolution of multiple key Campaigns domains (e.g., configuration, scheduling, reporting).
  • Drive domain decomposition, service boundaries, and data model design to improve scalability, performance, and operational excellence.
• Deliver high‑quality, scalable features
  • Lead the design and implementation of best‑in‑class web experiences using React and Type Script, backed by REST and Graph
    
    QL APIs.
  • Ensure backend systems are robust, observable, and performant, with an eye on peak traffic events. Scrutinize and reduce technical ambiguity and risk for upcoming projects through design reviews, technical spikes, and clear decision records.
• Create and improve engineering processes
  • Work with the Engineering Manager to ensure team adherence to solid engineering practices (testing, observability, rollout strategies, incident response).
  • Create, teach, and improve shared engineering processes and patterns that can be adopted by adjacent teams.
  • Uplevel adjacent processes, technology, and people by sharing best practices and reusable solutions.
• Influence beyond your immediate team
  • Act as the primary technical interface to other Campaigns and platform teams, ensuring cohesive end‑to‑end solutions.
  • Regularly…