Greenhouse ·
full-timeSoftware Engineer II - SMS International
Klaviyo · London, UK
Klaviyo is a marketing automation platform that provides e-commerce businesses with tools to manage communication channels including email, SMS, and push notifications. As a Software Engineer II on the SMS International team, you will focus on expanding SMS capabilities into new global regions and developing RCS messaging features. The role involves full-stack development, requiring you to build and scale new services while integrating them into the company's existing mobile marketing infrastructure. You will work within a small team to architect solutions, manage high-volume database queries, and maintain system performance using a stack that includes Python, Django, Go, and React. Daily responsibilities include collaborating on system design, managing CI/CD pipelines, and utilizing AI-assisted coding tools to deliver business outcomes. This position is well-suited for a developer with three to five years of experience who is comfortable working across both monolithic and microservices architectures. Candidates should have a strong background in cloud-based infrastructure, specifically AWS, and a demonstrated ability to debug performance issues in large-scale systems. An interest in international market expansion and mobile communication technologies is essential for success in this role.
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. About the Team This role is for the SMS International team that is part of Mobile Platforms. The Mobile Platforms team at Klaviyo is responsible for empowering the over 200,000 Ecommerce clients we work with on a global scale to deliver effective experiences on mobile devices. This team focuses on performance optimization and continuous development of our Mobile Marketing Channels (SMS, Push Notifications, In App Messages, WhatsApp and RCS), Mobile SDKs (iOS, Android and React Native). While Email was how Klaviyo began, Mobile messaging is truly the way of the future. The SMS International team within Mobile Platforms is responsible for the expansion of SMS capabilities into new countries and regions and is also spearheading the development of RCS as a new capability to be offered to customers alongside existing channels. We have an ambitious roadmap for 2026 and 2027 that puts the team at the heart of the company’s objectives and it is an exciting time to join the team! About the Role As a Fullstack Software Engineer II joining the SMS International team you will be working with a team of 4 other colleagues to deliver RCS and SMS International expansion to meet the company’s objectives. You will get the chance to build brand new services, understand how they fit into the bigger picture and plan how to architect and scale them successfully to serve our customers. Technologies we use (not exhaustive): Claude Code, with other LLM tools also available Python, Django, Go, React, RabbitMQ, Celery, MySQL, DynamoDB, Elasticache, Redis Amazon Web Services (EC2, RDS, Aurora, SQS etc.), Terraform, Kubernetes, Splunk, Buildkite, Grafana, and other modern DevOps tools What we are looking for 3-5 years of experience in a software engineering discipline Experience with full stack application development Experience working with both monolithic and microservices architectures Experience working with AI tools to deliver business outcomes Experience with database design that can withstand high query volumes Experience with CI/CD pipelines Experience debugging performance issues and improving application performance An interest and aptitude for collaboration across teams and disciplines Nice to Have Experience creating new services with scalability in mind. Exposure to large-scale system design Experience with AWS or any similar cloud provider Communication domain experience Our salary range reflects the cost of labour in the country where the job post is advertised. 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 in Local Currency: £68,000 — £102,000 GBP This role may require up to 10% travel for purposes such as new hire onboarding, client or partner work if applicable, team meetings, and industry events. Travel is coordinated in advance. Get 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
| Role | Software Engineer II - SMS International |
|---|---|
| Company | Klaviyo |
| Location | London, UK |
| Compensation | Not disclosed |
| Posted | 2026-09-30 |
| Deadline | Rolling |
Typical process for this type of role
A general guide — the exact steps for this specific listing may vary; check the original posting for details.
- 1ApplicationSubmit your resume through the apply link.
- 2ScreeningRecruiter reviews your background against the role.
- 3AssessmentA technical test, assignment, or coding round, depending on the role.
- 4Interview(s)One or more rounds with the hiring team.
- 5OfferOffer letter with compensation and start date.
Before you apply
0/4About Klaviyo
Klaviyo, Inc. is an AI-first B2C CRM platform founded in 2012 and headquartered in Boston. The company provides a unified solution that integrates marketing automation, customer service, analytics, and a data platform to help businesses manage customer relationships. By centralizing behavioral, transactional, and engagement data, Klaviyo enables brands to deliver personalized, omnichannel campaigns across email, SMS, WhatsApp, and mobile push notifications. The platform utilizes AI agents to automate marketing tasks, resolve customer service inquiries, and optimize campaign performance. Klaviyo currently serves over 205,000 brands across more than 100 countries, processing billions of events and managing billions of customer profiles daily to support business growth.
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