Senior Software Engineer, Klaviyo
Reliability
€92-138k
More information about location
3 days a week in office
The autonomous B2C CRM
Open for applications
The autonomous B2C CRM
1001+ employees
Open for applications
€92-138k
More information about location
3 days a week in office
1001+ employees
Company mission
Klaviyo is the only autonomous CRM built for B2C brands. Powered by its built-in data platform and AI insights, Klaviyo combines marketing automation, analytics, and customer service into one unified solution, making it easy for businesses to know their customers and grow faster.
Role
Who you are
- 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
- You are a cloud-native, platform-focused SRE who uses software to build and operate reliable production systems at scale
- You write and maintain production-quality code (e.g. Python, Go, or similar) to build internal platforms, automate operations, and improve system reliability
- You have built, deployed, and operated distributed, cloud-native systems and understand failure modes such as partial outages, dependency failures, resource saturation, and cascading impact
- You have experience operating containerized workloads and platforms (e.g. Kubernetes) in production, including deployment strategies, scaling behavior, and service networking
- You are comfortable participating in on-call rotations and diagnosing production issues
- You have designed and operated observability systems and know how to build actionable alerts that reflect real user and service impact
- You apply SRE concepts such as SLIs, SLOs, error budgets, and burn-rate–based alerting to guide engineering decisions and operational response
- You have hands-on experience with infrastructure as code and declarative configuration (e.g. Terraform, Kubernetes manifests, policy-as-code)
- You have performed capacity planning, load testing, and performance analysis for distributed services and platforms
- You routinely contribute to post-incident reviews and drive concrete, code-focused follow-up actions that prevent recurrence
- You are comfortable reviewing and contributing to technical designs, platform APIs, operational runbooks, and system documentation
- 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
Desirable
- Experience supporting security-critical platforms or building internal security tooling
- Familiarity with identity, access management, secrets management, or policy enforcement systems
- Experience operating systems at scale in cloud environments (AWS preferred)
- Background in resilience testing, fault injection, or chaos engineering
- A strong comprehension of algorithms and data structures at scale
What the job involves
- As a Senior Software Engineer, Reliability, you’ll ensure Klaviyo’s critical platforms are reliable, scalable, and sustainable while enabling rapid product development
- We treat reliability as a core product feature and use software engineering to solve complex systems and operational challenges
- Our work spans security, infrastructure, and software development, requiring us to understand systems and engineering
- We build complex, foundational solutions that must be extremely reliable, secure, and performant at global scale
- Our charter is to build and operate foundational services and infrastructure, define clear reliability objectives, reduce operational toil through automation, and continuously improve systems based on real production learnings
- The work is highly visible and directly impacts how Klaviyos build software and how customers experience Klaviyo every day
- As a Senior Software Engineer, Reliability, you will build and operate the platforms, systems, and services that underpin Klaviyo’s reliability and operational excellence
- Build and operate foundational, security-critical services with a strong emphasis on availability, scalability, latency, and fault tolerance
- Apply software engineering principles to automate infrastructure, reduce operational toil, and improve system reliability at scale
- Design, implement, and evolve systems using SRE best practices
- Define and refine SLIs, SLOs, and error budgets to guide engineering decisions
- Improve observability, alerting, and incident response to reduce mean time to detection and recovery
- Participate in on-call rotations with a focus on sustainable operations and automatic remediations
- Perform quantitative analysis to understand system behavior, capacity constraints, and scaling limits
- Identify systemic risks and reliability bottlenecks and drive long-term, preventative solutions
- Collaborate closely with product, platform, and security engineers to influence architecture early and ship reliable systems
- Mentor and pair with other engineers, helping raise the bar for reliability, operational maturity, and engineering excellence
- Klaviyo’s platform is primarily built with Python and React and runs on AWS. Engineers join us from a wide range of technical backgrounds and are supported in learning our stack
- Core technologies include:
- Python / Django / FastAPI
- MySQL / Redis / Memcached
- RabbitMQ / Celery / Apache Kafka / Apache Pulsar
- AWS / Terraform / Kubernetes
Our take
Klaviyo is a marketing firm helping growth-focused eCommerce brands drive more sales with super-targeted, highly relevant email, Facebook and Instagram marketing campaigns. From personalised newsletters to automated emails when customers abandon their shopping carts, the marketing automation platform makes it easy for businesses to capture, store, analyze, and predictively use their own data to drive measurable, high-value outcomes.
Klaviyo's CEO, Bialecki, believes that the main problem with e-mail marketing today is that there is a divide between two kinds of tools: analytics tools that help you understand what people are doing on a website, such as what products they are considering, and messaging tools that send them a marketing e-mail. Operating primarily within the retail and eCommerce industry, Klaviyo aims to solve this by offering a tool that brings together analytics and messaging. This allows companies to bring all of their first-party data into a single platform to get a deep understanding of their customers and then activate that data to deliver highly-targeted, personalised communications through email and SMS. In the process, Klaviyo's customers get a deep understanding of their consumers.
Klaviyo is a fast-growing company mainly due to its business model - the firm offers a concrete ROI for Klaviyo’s clients if the software persuades customers to make purchases by treating different types of customers differently. An IPO in 2023 has led to Klaviyo's release of Klaviyo AI, which empowers businesses to unlock revenue-driving opportunities and deliver exceptional customer experiences across channels. Still in its early days of public listing, it will be interesting to see how Klaviyo fares in the years to come.
Freddie
Company Specialist at Welcome to the Jungle
Meet the team
Devin Bhatia, Customer Success Manager
Our mission
Create exceptional customer experiences by providing immediate and long-lasting value, while empowering creators to own their growth.Insights
4% employee growth in 12 months
Company
Employee endorsements
Opportunities to learn
"Not only we have a good stipend to spend on learning but we also have development days every quarter, where we can switch off and focus on the areas..."
Company benefits
- Private medical insurance
- Medical
- Dental
- Vision
- Lifestyle spending account
- Commuter benefits
- Modern Health - wellness platform
- Parental leave
- Company equity
- Employee stock purchase plan
- Mental health benefits
Company values
- Put customers first: We prioritize our customers > customers’ customers > team > ourselves. We empathize deeply with our customers by walking in their shoes and solving their greatest pain points. We start with what’s best for the customer, not what’s best for us, and work backwards, delivering experiences our customers will talk about.
- Win together: We’re one team, we get to know each other, we’re okay with conflict and willing to disagree and commit. We are honest, direct, transparent, and respectful. We seek and incorporate diverse perspectives and assume good intent.
- We’re 1% done: We’re just getting started – our greatest products, work, and achievements are in front of us. We have a beginner’s mindset – we see the opportunities to build and improve and have the ambition to go after them. We benchmark against the best, aim to beat them, and celebrate when we do.
- Know the score: We’re clear about what success is for each project and how it ladders to our overall success. Results are what matter. Working hard is required, but it’s not success. We use data and past performance to motivate our future strategy.
- Be meticulous in your craft: We seek to do work so good that people rave about it. We are rigorous, thorough and prepared. We are or expect to be the experts everyone in the world turns to.
- Move fast, no shortcuts: Speed matters. We set ambitious deadlines, we like short cycles and being first to market. We don’t skip critical steps or requirements to make a date. We’re comfortable living in the grey and making judgment calls to decide what’s required and what’s not.
- Drivers wanted: No passengers — we’re proactive and engaged, and if we see something wrong it’s our responsibility to fix it or raise the issue to its owner. Have a vision and make sure it’s compelling. No job is beneath us. If it needs to get done, we’re happy to pick it up. We use and spend resources like they’re our own.
- Stay hungry, stay humble: We are insatiably curious learners; our slopes are very high. If we don’t know something, we’re world- class at figuring it out. We take calculated risks and sometimes make mistakes — we’re not perfect. When we fail, we learn from it and improve going forward. Feedback is a gift, even if it hurts sometimes. We don’t tolerate brilliant jerks.
Company HQ
Dublin, Republic of Ireland
Articles
Leadership
Andrew Bialecki
(Founder and Co-CEO)Co-founder and Co-CEO. Previously CTO at RockTech, Senior Engineer at Performable, Lead Engineer at Applied Predictive Technologies and an SDET Intern at Microsoft
Ed Hallen
(Chief Strategy Officer)Co-founder and currently our Chief Strategy Officer. Previously worked in Enterprise Business Development at Google, Summer Associate at Accel-KKR and Principal at Applied Predictive Technologies.
Chano Fernandez
(Co-CEO)Chano serves as the co-CEO, leading all go-to-market functions at Klaviyo. He previously led organizations at SAP, Workday, and Eightfold.
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