Software Engineer II - SMS International

Academic Key; Greater London; Hybrid; GBP 68,000 - 102,000; Full time

Job summary

Klaviyo is hiring a Fullstack Software Engineer II for the SMS International team. You will build and scale new services, architect scalable solutions, and work across mobile messaging channels to empower ecommerce clients worldwide.

You will collaborate with product and engineering peers, apply AI tools to business outcomes, and contribute to high‑performing, scalable systems in a modern cloud stack.

Qualifications

• 3–5 years of software engineering experience.
• Experience with full stack application development.
• Experience with monolithic and microservices architectures.
• Experience with AI tools to deliver business outcomes.
• Experience with database design for high query volumes.
• Experience with CI/CD pipelines.
• Ability to collaborate across teams and disciplines.

Responsibilities

• Build and scale brand new services within the SMS International team.
• Architect and implement scalable solutions across mobile messaging channels.
• Collaborate with cross‑functional teams to deliver reliable software.

Skills

Full stack development

AI tools experience

CI/CD pipelines

Performance debugging

Collaborative teamwork

Tools

AWS

DynamoDB

Redis

Kubernetes

Terraform

RabbitMQ

MySQL

Job description

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