Lead Software Engineer, Mobile Channels at Klaviyo

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 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. Massachusetts Applicants: It is unlawful in Massachusetts to require or administer a lie detector test as a condition of employment or continued employment. An employer who violates this law shall be subject to criminal penalties and civil liability. Our salary range reflects the cost of labor across various U.S. geographic markets. The range displayed below reflects the minimum and maximum target salaries for the position across all our US locations. The base salary offered for this position is determined by several factors, including the applicant’s job-related skills, relevant experience, education or training, and work location. In addition to base salary, our total compensation package may include participation in the company’s annual cash bonus plan, variable compensation (OTE) for sales and customer success roles, equity, sign-on payments, and a comprehensive range of health, welfare, and wellbeing benefits based on eligibility. Your recruiter can provide more details about the specific salary/OTE range for your preferred location during the hiring process. Base Pay Range For US Locations:$176,000—$264,000 USDGet to Know Klaviyo We’re Klaviyo (pronounced clay-vee-oh). We empower creators to own their destiny by making first-party data accessible and actionable like never before. We see limitless potential for the technology we’re developing to nurture personalized experiences in ecommerce and beyond. To reach our goals, we need our own crew of remarkable creators—ambitious and collaborative teammates who stay focused on our north star: delighting our customers. If you’re ready to do the best work of your career, where you’ll be welcomed as your whole self from day one and supported with generous benefits, we hope you’ll join us. AI fluency at Klaviyo includes responsible use of AI (including privacy, security, bias awareness, and human-in-the-loop). We provide accommodations as needed. By participating in Klaviyo’s interview process, you acknowledge that you have read, understood, and will adhere to our Guidelines for using AI in the Klaviyo interview Process. For more information about how we process your personal data, see our Job Applicant Privacy Notice. Klaviyo is committed to a policy of equal opportunity and non-discrimination. We do not discriminate on the basis of race, ethnicity, citizenship, national origin, color, religion or religious creed, age, sex (including pregnancy), gender identity, sexual orientation, physical or mental disability, veteran or active military status, marital status, criminal record, genetics, retaliation, sexual harassment or any other characteristic protected by applicable law. IMPORTANT NOTICE: Our company takes the security and privacy of job applicants very seriously. We will never ask for payment, bank details, or personal financial information as part of the application process. All our legitimate job postings can be found on our official career site. Please be cautious of job offers that come from non-company email addresses (@klaviyo.com), instant messaging platforms, or unsolicited calls. By clicking "Submit Application" you consent to Klaviyo processing your Personal Data in accordance with our Job Applicant Privacy Notice. If you do not wish for Klaviyo to process your Personal Data, please do not submit an application. You can find our Job Applicant Privacy Notice here and here (FR).