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# Senior Software Engineer, Internationalisation Platform

- **Company:** Klaviyo Inc.
- **Location:** Epsom, UK
- **Experience:** Expert
- **Contract:** Temporary contract
- **Skills:** HTML, JavaScript (Programming Language), Application Programming Interfaces (APIs), Artificial Intelligence, Amazon Web Services, Amazon Elastic Compute Cloud, Application Performance Management, ARM Architecture, Cascading Style Sheets (CSS), Cursor (Graphical User Interface Elements), Database Design, Software Debugging, Software Design Patterns, Distributed Systems, Django Web Framework, Amazon DynamoDB, Github, Instant Messaging Technology, JSON, Python (Programming Language), Memcached, MySQL, RabbitMQ, Redis, Software Engineering, Systems Architecture, TypeScript, Eslint, Klaviyo Email and SMS Marketing, ReactJS, Fastapi, Webpack, Stripe, Kubernetes, Cassandra, Cloudflare, Graphql, Celery, Restful APIs, Terraform, Splunk, Golang, Microservices
- **Published:** May 13, 2026
- **Apply:** https://www.apply4u.co.uk/jobs/x/36177359/

## About the Role

A strong interest in internationalisation, localisation, and translation.
A desire to serve our international customers and expand Klaviyo's capabilities.
5+ years of demonstrable experience delivering high-quality, customer-facing software.
Deep understanding of complex systems (or similar large-scale distributed systems) and strong systems thinking, with a proven ability to scale, observe, and maintain services.
Familiarity with full stack development concepts and a strong aptitude to learn.
Experience working with both monolithic and microservices architectures.
Experience with database design that can withstand high query volumes.
Experience debugging performance issues and improving application performance.
An interest and aptitude for collaboration across teams and disciplines.
An understanding of challenges in developing software across multiple languages and catering to non-English speaking users.
Thrives in a fast-paced, customer focused, and strategic environment.
A track record of prioritizing the needs and success of the company overall above the immediate needs of the team.

Nice to Have

Proven experience with large-scale system design and driving the technical/architectural evolution of a product area.
Experience with AWS or any similar cloud provider.
Experience with billing systems in multiple currencies.

Technologies We Use (not Exhaustive)

React, TypeScript, JavaScript, HTML, CSS
Babel, Webpack, Eslint, Prettier
REST, GraphQL, JSON Schema, JSON:API
CDNs (Fastly, Cloudflare)
GitHub, BuildKite
MySQL, Redis, Pulsar, Memcache
Python, Django, FastAPI, Go, Gin, React, RabbitMQ, Celery, MySQL, DynamoDB, Cassandra, Redis
DeepL, Smartling, Stripe
Amazon Web Services (EC2, RDS, Aurora, AWS Translate, etc.), Terraform, Kubernetes, Splunk, Chronosphere, Cortex, DX, and other modern DevOps tools
Bedrock, Claude, Cursor, LangChain, OpenAI, Gemini

## Description

You will lead and drive the design and execution of complex, business-critical projects across the Internationalisation platform.
You will be responsible for implementing new functionality and establishing design patterns for complex, multi-component systems.
You will take full lifecycle ownership of features and projects, driving requirement refinement and setting the pace for all phases of execution.
You will proactively collaborate with cross-functional partners to influence product requirements and communicate technical needs to other teams.
You will be an active participant in all team processes and accountable for meeting the health and operational excellence (SLOs) of your area of ownership.
You will help interview new engineering team members and actively mentor junior engineers in your product area., 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 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.
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