Senior SDET - Browser & Extension Testing

The Senior SDET - Browser & Extension Testing will own test strategy, quality architecture, and the automated regression infrastructure for Securly's onboard filtering project — building the test systems that ensure a safety-critical Chrome extension works correctly for millions of students and keeps working through every browser update and policy change.

The onboard filtering project is a high-risk architecture change to a widely-deployed extension. A regression in allow/block decision logic, cache invalidation, or bypass prevention could expose students to inappropriate content or disrupt school operations. The test infrastructure you build is the last line of defense before production.

At L5, this is an engineering leadership role, not a QA role. You will define what 'production-ready' means for a safety-critical student product, enforce that standard through CI/CD quality gates, and contribute to extension development directly.

• Define what 'passing' means for the onboard filtering project: establish written quality criteria covering correctness, security, and performance that gate production releases.
• Design and implement automated test suites covering block/allow decisions, iframe handling, cache invalidation, TTL expiry, fallback behavior, and filtering decision engine edge cases.
• Build CI/CD quality gates that prevent regressions from reaching production; own the pipeline configuration and ensure the quality bar is enforced, not advisory.
• Model bypass threats systematically: document how students exploit timing windows, iframes, DOM manipulation, redirect chains, and DNS TTL behavior — then build automated tests that catch those bypasses.
• Measure and establish written performance baselines: page load latency impact, service worker memory usage, cache sync overhead across realistic Chromebook hardware profiles.
• Contribute to Chrome extension development work in TypeScript/JavaScript alongside test responsibilities.
• Serve as the team's expert on bypass threat modeling: your analysis of how students circumvent filtering is an input to the implementation team's architecture decisions.
• Mentor engineers on test architecture as a first-class discipline.

• You think like an attacker when writing tests — you do not test the happy path and call it done. You document attack vectors so the implementation team designs against them.
• You have shipped production Chrome extensions and built the test infrastructure around them. You know both sides of the work.
• You treat test architecture as a first-class engineering discipline. A feature without a regression suite is not finished.
• You define what 'quality' means on a safety-critical product and produce written criteria that hold the codebase to that standard.
• You contribute to development, not just testing — this is an L5 engineering role, and your TypeScript ships alongside your test suites.
• Your bypass threat model documents are used by the implementation team to make better architecture decisions.

L5 at Securly is a Staff Engineer. You are the technical owner, not just an implementer.

• Drive technical direction for your initiative end-to-end: from architecture to production, with minimal oversight from your engineering manager.
• Identify and resolve ambiguity in requirements, system boundaries, and design tradeoffs without waiting for a fully-formed spec.
• Mentor L3/L4 engineers on the team: code reviews, design feedback, pairing, and raising the bar for what production-quality work looks like.
• Partner with your L6 technical lead and the Distinguished Engineer on architectural decisions, surfacing tradeoffs clearly rather than deferring them upward.
• Contribute to cross-team engineering standards: you are expected to influence practices beyond your immediate squad.
• Translate technical context into clear written artifacts that non-engineers (PM, Support, Leadership) can act on.
• Participate in on-call rotation and own the full incident lifecycle for your system: detection, diagnosis, resolution, and retrospective.