Software Development Engineer in Test

Harmonic exists to help enterprises adopt AI safely and at scale. We hold ourselves to that same standard. Everyone here actively leverages AI tools to perform their best work, from deep research and writing to building robust processes and automating complex workflows. We expect every new hire to bring a genuine curiosity for AI and a commitment to using it to work smarter, faster, and with greater creativity.

For some, this involves tinkering and remaining open to emerging tools; for others, it means architecting entirely new systems with AI at the core. We will be transparent about expectations for every role and provide the tools and support needed for you to thrive.

Our Product Delivery team is the engine that turns vision into impact. We ship early and often, getting valuable features into the hands of customers quickly and iterating from there. We work in the open by default, sharing progress and ideas, and we trust each other to own outcomes. We’re a small but mighty crew where every person plays a critical role and we’re committed to using AI to work smarter and faster.

We're looking for a Software Development Engineer in Test (SDET) to build and maintain automated testing infrastructure across our products. You'll design test frameworks, set up cross-platform test environments, hunt down bugs, integrate tests into CI/CD pipelines, and work closely with engineers to keep our quality bar high. This is a hands-on, adaptable role where you'll need to apply yourself wherever testing is needed most.

Our product protects enterprises as they adopt AI tools. We build everything from customer-facing portals and browser extensions that monitor AI interactions in real-time, to endpoint agents and MCP gateways that enforce security policies. Rigorous, scalable test coverage across this diverse stack is critical to our success. AI-tool fluency is expected. The team uses AI daily, and the product itself secures enterprise AI adoption, so familiarity cuts both ways.

Design, implement, and maintain test frameworks for our UI, browser extensions, endpoint agent, or backend services - you'll need to apply yourself wherever QA is needed

Build and run cross-platform tests on Windows, macOS, and Linux - set up test environments to validate our endpoint agent doesn't break user systems

Expand, run, and investigate load tests to validate system behaviour at scale and ensure we can handle growth

Investigate bugs, write failing tests, get them fixed - file detailed tickets, write tests that expose the issue, fix it yourself if you can, or partner with engineers to verify the fix

Integrate tests into CI/CD - add tests to GitLab CI pipelines, set up quality gates and detailed test reports, keep tests fast and reliable

Monitor, triage, and improve - file detailed bugs in Jira, escalate critical issues quickly, track test coverage, shape the QA roadmap

5+ years as an SDET building and maintaining automated test infrastructure

Strong programming skills in at least one of TypeScript, Java, or Rust

Experience with modern test frameworks and willingness to learn new ones (the stack includes Jest, Playwright, Bun test, Vitest, JUnit5, Selenium, and Rust's native testing via cargo test)

Cross-platform testing experience, comfortable setting up environments, debugging platform-specific issues, and working with VMs or real machines

CI/CD pipeline knowledge, integrating tests into GitLab CI or similar, setting up quality gates, and making reports useful

Demonstrable experience using AI tools to speed up workflows and boost productivity

Solid debugging skills and proficiency with Git, code review, and CI/CD systems

Take proactive ownership of quality, seeking out risks before they reach production

Bring a thorough, creative approach to complex and often custom testing challenges

Write test code with the same rigour, readability, and discipline as production code

Balance broad coverage with observability, reliability, and fast, meaningful feedback

Thrive in a fast-paced startup environment where ambiguity and continuous improvement are the norm

This isn't just a job - it's a chance to help define a category. Harmonic Security was named to the Rising in Cyber 2026 list, and we're just getting started. We're building at the intersection of AI and security, carving out an emerging market where the rules haven't been written yet, and the people who join now will write them.

We believe today's talent is tomorrow's success, and we're committed to creating an environment where you can do the best work of your life.

Recognized momentum - We made the Rising in Cyber 2026 list, a signal that the market is taking notice

Rare market opportunity - Join early in a category-defining company at the convergence of AI and security, where your work directly shapes how enterprises tackle one of the biggest unsolved problems in tech

Competitive pay and meaningful equity - A real stake in Harmonic's success, not a token gesture

Comprehensive benefits - pension plan and flexible hybrid work

A small, high-trust team that values transparency, creativity, and continuous learning - no politics, no bureaucracy

Thoughtful leadership - that cares deeply about your growth, not just your output

Annual global off-sites - past trips include Lisbon, Portugal and Nashville, TN

Real ownership - you'll shape the product, the culture, and the direction of the company from day one

🌱 Flourish in the Unknown

We embrace new, unfamiliar situations that require initiative and rapid decision-making. We orient ourselves quickly and deliver results with minimal guidance.

🔥 Never Full

We raise our hands, take on challenges, and assist others whenever possible. We hunger for opportunities to learn and do more.

🤝 Perfect Harmony

We support one another to create cohesion and unity. We collaborate openly, share feedback honestly, and help everyone produce their best work