Hybrid SDET for AI Security Platform

Harmonic; Greater London; Hybrid; GBP 75,000 - 110,000; Full time

Benefits offered by this job

Equity ownership

Hybrid work

Annual off-sites

Competitive pay

Pension plan

Job summary

Harmonic is hiring a Software Development Engineer in Test to design and maintain automated testing infrastructure across our security platform. You will build cross‑platform test environments, expand load testing, and work closely with engineers to keep our quality bar high as we scale AI-powered products.

We value AI fluency, strong debugging, and ability to own testing from development through deployment. This is a hybrid role with a concrete path to impact in a fast-paced startup environment.

Qualifications

• 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 (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.

Responsibilities

• 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, escalatee critical issues quickly, track test coverage, shape the QA roadmap

Skills

SDET expertise

Cross-platform testing

CI/CD pipelines

Tools

Jest

Playwright

Selenium

JUnit5

cargo test

Job description

Harmonic is hiring a Software Development Engineer in Test to design and maintain automated testing infrastructure across our security platform. You will build cross‑platform test environments, expand load testing, and work closely with engineers to keep our quality bar high as we scale AI-powered products.

We value AI fluency, strong debugging, and ability to own testing from development through deployment. This is a hybrid role with a concrete path to impact in a fast-paced startup environment.