Senior GTM Partner Systems Engineer

About the team

Our GTM Systems team sits at the center of Klaviyo's go-to-market engine, powering the operational infrastructure that connects marketing, sales, partnerships, and customer success. We build and own the systems that enable our teams to move quickly, trust their data, and focus on what matters most: helping our customers grow.

Our GTM Systems Partner team is a small group of technical builders owning the Salesforce platform and its integrations across our full GTM stack — from lead routing and lifecycle management to the external-facing partner portal and its integrations with partner management and payment systems data.

About the role

As a Senior Systems Engineer on the GTM Systems Partner team, you will own the enterprise systems end-to-end — from understanding the business process, to engineering the right solution, to measuring whether it moved the needle. You will own delivery, platform health, and code quality across a GTM stack — including the external-facing partner portal by sizing and building features, maintaining platform health, and shipping reliable integrations across our GTM stack. This is a high-craft, high-ownership role for someone who wants to write great code, drive quality standards, and see their work translate directly to Klaviyo’s goals.

How you'll make an impact

• Own delivery of Salesforce solutions — Apex, Lightning Web Components, Flow, and integrations — from sprint planning through deployment, applying engineering best practices (DRY, SOLID, KISS) and holding a high bar for code quality through GitHub-based pull request reviews.
• Develop and maintain integrations between Salesforce and the broader GTM stack, including the external-facing partner portal; ensure reliable, secure data flows across partner management and payments while prioritizing strict access and permission governance.
• Triage and resolve high-impact platform and data issues quickly, owning the technical fix and communicating status clearly to the Product Owner and business partners.
• Use AI tools as part of your daily engineering workflow to ship faster, explore unfamiliar systems, and automate repetitive work — and help teammates build the same habits.
• Partner with the Product Owner and Architect during story refinement to size work accurately, surface technical constraints early, and ensure stories are fully ready before sprint planning.
• Mentor junior developers through code reviews, engineering standards, and pairing — accelerating the team's shift to professional-grade, git-based development practices.