Senior SDET

About Harmonic Security

Harmonic Security lets teams adopt AI tools safely by protecting sensitive data in real time with minimal effort. It gives enterprises full control and stops leaks so that their teams can innovate confidently.

We are led by cybersecurity experts and backed by top investors including N47, Ten Eleven Ventures, and In-Q-Tel.

We’ve achieved early traction and strong product-market fit with a world-class team, and we’re now focused on scaling quality, reliability, and confidence as our product footprint expands. This is an opportunity to join early, build the automated testing foundations that keep a complex, cross-platform security product dependable, and help define the quality bar for a new category of AI security.

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 security agents and (Model Context Protocol) MCP gateways that enforce security policies. Rigorous, scalable test coverage across this diverse stack is critical to our success.

• 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 - 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 Git Lab CI pipelines, set up quality gates and detailed test reports, keep tests fast and reliable.
• Monitor, triage, and improve - file detailed bugs in Jira, elevate critical issues quickly, track test coverage, shape the QA roadmap.

• You've improved test infrastructure:
  You've enhanced and maintained test frameworks wherever needed - UI, browser extensions, endpoint agents, or backend services.
• Cross‑platform confidence:
  Our products ship to Windows, macOS, and Linux with confidence.
• Load testing validates scale:
  The team knows the system can handle growth before deploying to more users.
• Bugs get caught and fixed fast:
  Your failing tests expose issues quickly, and you work with engineers to get them resolved.
• CI/CD is reliable:
  Tests are integrated smoothly, reports are clear, pipelines stay green, and engineers know why things break.
• Coverage is tracked and improving:
  You monitor what's tested and what's not, continuously filling gaps.

• 5+ years as an SDET building and maintaining automated test infrastructure.
• Strong programming skills in at least one of Type Script, Java, or Rust.
• Experience with modern test frameworks and willingness to learn new ones - at Harmonic we use Jest, Playwright, Bun test, Vitest, JUnit5, Selenium, and Rust's native testing framework (cargo test).
• Cross‑platform testing experience on Windows, macOS, and Linux - comfortable setting up test environments, debugging platform‑specific issues, and working with VMs or real machines.
• CI/CD pipeline knowledge - you…