Software Engineer II, Test Frameworks & Tooling

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. Why You Should Join the Test Frameworks and Tooling Team Engineering confidence is our primary product. We are not testers, but rather infrastructure engineers building the sophisticated automation and CI/CD frameworks that make deploying to production a non-event. Our mission is to architect the systems, repository standards, and automated guardrails that empower every engineer in the company to ship at terminal velocity with total confidence. By building the foundational tools that guarantee production readiness, you will play a direct role in driving Sev-1 incidents toward zero and ensuring that our organization can move fast without the fear of breaking things. What You'll Achieve: Key Responsibilities As a core member of the team, you will own the execution of critical projects and contribute to the evolution of our testing ecosystem: • Own and Enhance Frameworks: Take ownership of our integration and E2E testing frameworks across both backend and frontend stacks. You will ensure they are fast, reliable, and easy for other teams to adopt. • CI/CD Integration: Contribute to how we execute tests within our CI system. You will focus on optimizing feedback loops so engineers know exactly where they stand in minutes. • Establish Standards: Help define and implement general rules for our repositories, ensuring consistency in how unit tests are written and how code quality is measured. • Scalable Feature & Coverage Contribution: Actively develop new tools that simplify complex testing scenarios while identifying and backfilling critical testing gaps at scale. You will build systems for data mocking and service isolation that ensure high-fidelity coverage across our most complex application flows. • AI-Driven Quality Innovation: Help lead the charge in leveraging AI to accelerate our testing lifecycle. You will explore and implement AI-powered tools for automated regression detection, flaky test analysis, and intelligent test generation to decrease time-to-completion for features. • Collaborative Problem Solving: Partner with feature teams to troubleshoot flaky tests and identify gaps in our current coverage, making proactive suggestions to improve our overall safety net. • Operational Excellence: Monitor the health of our test suites and CI pipelines, taking pride in maintaining a stable and performant environment for the entire engineering organization. What Makes This Role Exciting • Direct Impact on Stability: Your work is the primary line of defense against Sev 1 incidents. When the platform stays up and customers stay happy, it is because of the systems you help maintain. • Full-Stack Visibility: Because you own the E2E suite, you will gain a deep understanding of how our entire ecosystem fits together, from frontend UI components to complex backend microservices. • Autonomy and Growth: While we provide the vision, you provide the execution. You will have the space to own your work end-to-end, propose technical improvements, and see your suggestions implemented company-wide. • High-Leverage Work: You are not just building one feature for one customer. You are building the tools that hundreds of your fellow engineers use every single day to do their jobs better. Who You Are: • Analytical Problem Solver: You have 2+ years of software engineering experience with a focus on writing clean, maintainable code. You excel at debugging complex issues and performing root-cause analysis, using those learnings to implement systemic improvements that prevent future regressions. • Quality Advocate: You find satisfaction in a well-organized test suite. You understand that testing is a fundamental part of the development lifecycle, not an afterthought. • Technical Generalist: You are comfortable working across the stack. Whether it is debugging a React component in an E2E test or optimizing a Python integration test, you are ready to dive in. • AI-Forward Thinker: You are excited about the intersection of AI and Software Quality. You are eager to help us leverage AI to automate test generation, identify flaky patterns, and accelerate the overall development lifecycle. • Ownership Mindset: You do not just wait for tickets. You look for ways to make things better. You take pride in owning a project from the initial PR to its successful deployment and monitoring. • CI/CD Familiarity: You have experience with, or a strong desire to learn, CI/CD tools and understand how automated testing fits into a modern deployment pipeline. Technologies we use (not exhaustive): • Backend: Python, Django, Go • Frontend: React, TypeScript, JavaScript • Testing Frameworks: Playwright, Cypress, Pytest, Jest • Infrastructure and CI: AWS, Kubernetes, Terraform, Helm, Buildkite • Data: MySQL, Redis, Kafka • AI Tools: Integration with Claude, Cursor, Copilot, or internal AI enablement frameworks Massachusetts Applicants: It is unlawful in Massachusetts to require or administer a lie detector test as a condition of employment or continued employment. An employer who violates this law shall be subject to criminal penalties and civil liability. Our salary range reflects the cost of labor across various U.S. geographic markets. The range displayed below reflects the minimum and maximum target salaries for the position across all our US locations. The base salary offered for this position is determined by several factors, including the applicant’s job-related skills, relevant exper