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 youre a close but not exact match with the description we hope youll still consider applying. Want to learn more about life at Klaviyo Visit 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 Klaviyos 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 youll provide technical leadership to a group of engineers building and scaling the services that power Klaviyos mobile messaging pipeline end-to-end. Youll 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 youll contribute to architecture code and mentorship while shaping the future of mobile messaging at Klaviyo.

If youre 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 Klaviyos 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 Klaviyos 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
• Youve already experimented with AI in work or personal projects and youre excited to dive in and learn fast. Youre hungry to responsibly explore new AI tools and workflows finding ways to make your work smarter and more efficient.

Technologies We Use:

• Python Go
• AWS Terraform DynamoDB Redis SQL
• Kafka

Location:

This is a hybrid role based in Boston with 3 days in office and 2 days remote per week.

We use Covey as part of our hiring and / or promotional process. For jobs or candidates in NYC certain features may qualify it as an AEDT. As part of the evaluation process we provide Covey with job requirements and candidate submitted applications. We began using Covey Scout for Inbound on April 3 2025.

Please see the independent bias audit report covering our use of Covey here