Lead Software Engineer, Mobile Channels

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 klaviyo.com/careers to see how we empower creators to own their own destiny. Why You Should Join the Mobile Channels Team: The Mobile Channels team at Klaviyo powers text messaging across Klaviyo's platform — SMS, RCS, WhatsApp, and a growing set of future text messaging channels. As brands increasingly rely on mobile to reach their customers, our team builds the infrastructure that makes high-throughput, reliable delivery possible across a complex, multi-channel landscape. We own the systems that connect Klaviyo customers to their audiences through the fastest and most personal communication channels available. As a Lead Software Engineer on the Mobile Channels team , you'll provide technical leadership to a group of engineers building and scaling the services that power Klaviyo's mobile messaging pipeline end-to-end. You'll drive technical strategy, own critical components of the delivery infrastructure, and help the team navigate the unique challenges of multi-channel compliance, carrier regulations, provider integrations, and global deliverability. This is a hands-on technical leadership role where you'll contribute to architecture, code, and mentorship while shaping the future of mobile messaging at Klaviyo. If you're excited about building systems that deliver millions of messages across channels with speed and reliability — and leading a team at the center of one of Klaviyo's fastest-growing product areas — Mobile Channels is the place to do it. How You Will Make a Difference: Lead a team of engineers building and scaling Klaviyo's mobile messaging infrastructure across SMS, RCS, WhatsApp, and future channels Own and drive the architecture of key components in the mobile messaging pipeline — from message ingestion and routing to provider delivery and status tracking Design and implement scalable, high-throughput services in Python and Go Build systems that ensure reliable delivery at scale while managing carrier compliance, opt-in/opt-out requirements, throughput limits, and international messaging regulations Contribute directly to architecture and code, driving best practices and quality Collaborate cross-functionally with product, deliverability, compliance, and platform teams to expand mobile channel capabilities Grow and mentor engineers while helping shape the future of mobile messaging at Klaviyo Transform workflows by putting AI at the center, building smarter systems and ways of working from the ground up Who You Are: 8+ years of engineering experience with strong backend and systems design skills Proficient in Python and/or Go and be able to rapidly learn the other Comfortable coding and reviewing complex systems — this is a hands-on role Experienced working with high-throughput distributed systems Skilled in system design and scaling infrastructure using AWS Strong business and product mindset — you think beyond the code to understand customer impact and commercial value Able to bring clarity to ambiguous requirements, breaking down undefined problems into actionable plans Self-led and driven to deliver incrementally — you ship value early and iterate Bonus: Experience with SMS/MMS infrastructure, RCS, WhatsApp Business API, carrier integrations, telecom APIs, or messaging compliance Clear communicator and collaborative team player Able to thrive in a hybrid team and deliver in a high-autonomy environment You've already experimented with AI in work or personal projects, and you're excited to dive in and learn fast. You're hungry to resp ... (truncated, view full listing at source)