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Lead Software Engineer, SMS International

  • London, UK
  • Engineering

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 to see how we empower creators to own their own destiny.

Klaviyo is growing by leaps and bounds; as a result, we’ve recently established our SMS International team! With the explosive growth of SMS as a channel for customer communication, Klaviyo’s SMS offering is on the path toward market dominance. This team will focus on building and scaling a world-class messaging platform across the world. 

As a Lead Software Engineer joining the SMS International team you can expect to be deeply involved in technical discussions on how we scale our systems, build out and monitor new features, and grow the team. Another big focus of the role will be to build functionality that is reusable and extensible so that we can launch SMS in countries quickly.

The role will allow you to work with multiple stakeholders to provide the best in class service and reliability to connect a wide range of customers, from entrepreneurs to enterprises, with their end users. The messaging platform for Klaviyo delivered over 71 million SMS messages and 5.5 billion emails during BFCM 2022 (Black Friday/Cyber Monday). Engineers come to Klaviyo with experience in a variety of languages and from a number of disciplines. All engineers are expected to become extremely proficient in the technologies we use (not exhaustive): 

  • Python, Django, Celery
  • MySQL, Cassandra, RabbitMQ, Redis, Pulsar
  • React, Typescript, Front end best practices
  • Amazon Web Services (EC2, RDS, Aurora, etc.), Fastly Cache, Kubernetes
  • Twilio, Sendgrid, Firebase, APNS

How You Will Make a Difference 

  • Build and improve systems for high volume message delivery using multiple engagement channels. 
  • Provide technical leadership to drive architectural decisions across multiple teams and provide solutions for complex problems around scalability, throughput, performance etc.
  • Strive towards a cohesive technical vision across multiple roadmap items that are built across multiple teams.
  • Be a technical point of contact for the team for various projects and features where there are dependencies.
  • Defines technical strategy within their scope and executes to improve the functional area's products, infrastructure, or processes.
  • Mentors multiple engineers to develop new technical leadership for the company.

Who You Are 

  • Have 8+ years of experience and have architected, built and delivered at least two complex systems.
  • Experienced with cloud-based systems development and deployment, AWS preferred; experienced designing and operating systems for very high volume workloads and web-scale data.
  • Have proven that you can build & scale complex distributed systems including solving problems in sustainable ways, balancing pragmatic development with ideal architecture, breaking through technical obstacles with vigor, and leading teams through incidents and maintenance by working side by side with them in the trenches.
  • Love digging into performance and scalability issues to drive breakthrough solutions--whether it's a slow loading UI 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.
  • Enjoy shipping code early & often in an agile fashion, pairing with product management to craft better software by soliciting feedback from thousands of end users. 
  • Authorisation to work in the UK without restriction

Klaviyo in EMEA : As part of the Klaviyo team you will be looked after with some great benefits locally in EMEA including equity for all, private health cover for you and discounted for your household, financial and professional coaching, a generous annual learning allowance (£2.5k), 22 weeks full pay primary care giver leave (16 week secondary) and free books (yes, any books!) to name a few.

Get to Know Klaviyo

Klaviyo is a world-leading marketing automation platform dedicated to accelerating revenue and customer connection for online businesses. Klaviyo makes it easy to store, access, analyze and use transactional and behavioral data to power highly-targeted customer and prospect communications. The company's hybrid customer-data and marketing-platform model allows companies to grow by fostering direct relationships with customers, without giving up their valuable data to popular big-tech ad platforms. Over 265,000 innovative companies like Unilever, Custom Ink, Living Proof and Huckberry sell more with Klaviyo. Learn more at .

If you are a California, Colorado, Rhode Island, Washington, New York City, or Jersey City resident and this role is a remote role, you can receive additional information about the compensation and benefits for this role, which we will provide upon request. Requests can be submitted here . Additional information regarding benefits can be found at .

      • 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.


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