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Posted 19 June, 2026

Sr. Software Engineer, Messaging Infrastructure

Klaviyo
Dublin, IE Full Time
Reference: 102_699685_7774823003

About Klaviyo

Klaviyo is a leading marketing automation platform that helps businesses grow by delivering personalized experiences. Our mission is to empower creators to own their destiny. We believe in providing an exceptional developer experience that enables our engineering teams to build and ship high-quality software efficiently and with confidence.

About the Team

The Messaging Infra organization at Klaviyo is focused on high-growth customer engagement through various messaging channels (email, SMS/MMS/RCS, mobile push, WhatsApp, and more). We work with multiple stakeholders to provide best-in-class service and reliability to connect a wide range of businesses, from entrepreneurs to enterprises, with their end users. The messaging platform is a mission-critical system, responsible for delivering billions of messages, and must be architected for massive scale and reliability.

How You Will Make a Difference

  • In this role, you will own and build features/services that hundreds of thousands of Klaviyo customers rely on daily to drive their business forward.
  • Work on crafting our highly-scalable, highly-available campaign pipeline that processes and delivers hundreds of millions of messages daily growing to billions scale.
  • Collaborate radically with teams and stakeholders across Klaviyo on designs, implementations, and engineering practices.
  • Learn new technologies, bring them to the team and apply them to evolve our systems to the next level.
  • Help us improve our experimentation and development processes, and mentor other engineers on the team.
  • Participate in the technical interview process to help maintain a high bar for our growing teams
  • Contribute to the company as a subject matter expert, constantly pushing yourself to be a better engineer and to level up all of your peers within your team and within Klaviyo.

Who You Are

  • Have 4-6+ years of experience in a software engineering discipline and have architected, built and delivered at least one complex system.
  • Experience on large-scale system architecture, technologies and patterns. Have a good understanding of their pros/cons and use scenarios, able to apply them to system design by making appropriate tradeoffs to meet the business needs best.
  • Love digging into performance and scalability issues to drive breakthrough solutions-- whether it's a performance degradation or too many clicks in a workflow, a database query timing out, or a queue that just won't drain. You recognize all problems can be solved.
  • Passionate about growing and improving a product daily using a data driven mindset, familiar with system monitoring and alerting techniques.
  • Proven experience with being a coach and a mentor for team members and helping them grow.
  • Like working on small, high-performing autonomous agile teams. At Klaviyo, you will have ownership of features, but you'll collaborate radically with everyone to make sure we produce the right solution.

Technologies we use (not exhaustive):

Languages & Frameworks: Python, Django, React

Data & Infrastructure: MySQL, Redis, Memcached, Apache Zookeeper, Apache Pulsar

Cloud & DevOps: AWS (EC2, RDS, Aurora), Terraform, Jenkins

Location & Work Model:

This role is based in Dublin, Ireland and follows a hybrid working model. Klaviyo supports work authorization and relocation for this position.

At Klaviyo, we enjoy tackling meaningful engineering challenges and value people who take ownership, learn continuously, and collaborate openly. We are committed to building inclusive teams and encourage applications from candidates of all backgrounds.

Klaviyo is growing fast and we have openings for all skill levels across all of our teams. Learn more about our engineering culture at https://klaviyo.tech

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