Senior Software Engineer 5 — Validation & Safety Platform

Netflix; Warszawa; On-site; PLN 300,000 - 420,000; Full time

Job summary

Netflix is seeking a Senior Software Engineer to advance the Validation & Safety Platform. You will design systems used by thousands of engineers and agents, balancing platform ownership with API exposure and secure sandboxing for test infrastructure access.

The role emphasizes building automated quality gates, agent-safe tooling, and scalable safety signals to ensure code correctness across agent-generated work.

Qualifications

• Experience building or operating a developer/platform used by many teams.
• Familiarity with LLM-based evaluation systems, agent trajectory scoring, or similar.
• Hands-on with mutation testing, static analysis, or test-selection systems.

Responsibilities

• Design and build validation and safety products used platform-wide: test generation, coverage and safeguards, deterministic and predictive test selection, and mutation testing at scale.
• Build the polyglot static analysis layer that gives agent-generated code an automated, language-agnostic first quality gate.
• Develop agent-specific safety signals: detect prompt flakiness, evaluate agent trajectories against execution traces, and score semantic correctness of agent-generated code.

Skills

Platform mindset

Cross-functional collaboration

Security-minded

Agent tooling experience

Education

Bachelor's/Master's in CS or related field

Tools

LLM-based evaluation systems

Mutation testing tools

Static analysis tools

Job description

Netflix is one of the world's leading entertainment services, with over 300 million paid memberships in over 190 countries enjoying TV series, films and games across a wide variety of genres and languages. Members can play, pause and resume watching as much as they want, anytime, anywhere, and can change their plans at any time.

About The Team

The Validation & Safety Platform is one of three pillars inside the new System Health, Validation & Insights Platform group in Productivity Engineering. Our mandate: catch safety and correctness regressions in human-written or agent-generated code before they reach production.

Netflix's agent fleet now writes, tests, refactors, and deploys code continuously across every domain. As agent volume grows, the constraint shifts from producing changes to knowing which ones are safe. Quality assurance can no longer be a human-gated step at the end of a PR — it has to be embedded at every stage of the developer loop, proactive and automated.

Today the team runs the validation and safety gates for the fleet: automated test generation, coverage and safeguards show teams where they stand. We're extending to other safety signals built specifically for agent-generated code, so we can judge whether a change is genuinely correct as agents write and modify code at scale.

About The Role

We are looking for a Senior Software Engineer to help build the next generation of this platform: tools and guardrails that keep pace with an engineering org where a growing share of code is agent-generated.

You will design systems that thousands of engineers and their agents depend on, make build-vs-extend calls on what the platform should own versus expose through an API, and bring a security-conscious view to how autonomous agents get sandboxed, scoped, and safely given access to test infrastructure.

Key Responsibilities

• Design and build validation and safety products used platform-wide: test generation, coverage and safeguards, deterministic and predictive test selection, and mutation testing at scale.
• Build the polyglot static analysis layer that gives agent-generated code an automated, language-agnostic first quality gate.
• Develop agent-specific safety signals: detect prompt flakiness (an agent producing inconsistent output across identical prompts or seeds), evaluate agent trajectories against execution traces, and score semantic correctness of agent-generated code against the original requirement, the agent's own stated intent, and observed behavior change.
• Define clear platform capabilities and make deliberate build-vs-buy, build-vs-extend calls as the platform's scope grows.
• Apply sound judgment on agent sandboxing, scoping, and data redaction wherever the platform gives agents access to test infrastructure or execution environments.

Who You Are

• Experienced building and operating a platform used by other engineering teams — you think about your product as a platform, not a one-off tool.
• Comfortable making product calls: what capability the platform should own, what it should expose as an API, and when to extend versus build new.
• An advanced user of agentic coding tools — you work daily with hooks, MCPs, and context management, even if you haven't built an agentic platform yourself.
• Security-minded: you have a working understanding of agent sandboxing, scoping, and redaction, even if it isn't your primary background.
• A strong communicator who can document technical tradeoffs clearly for both engineering and non-technical stakeholders.
• An advocate for a strong testing culture: familiar with test frameworks, code coverage tooling, CI systems, and post-deployment verification.

Experience We'd Be Excited About

• You have designed or operated developer-platform infrastructure: distribution, CI/CD, or versioning systems used by many teams.
• You have built or integrated LLM-based evaluation systems (LLM-as-judge, agent trajectory scoring, or similar).
• You have worked with mutation testing, static analysis, or test-selection systems at scale.
• You have hands‑on experience sandboxing or scoping agent access to sensitive systems or data.

Inclusion is a Netflix value and we strive to host a meaningful interview experience for all candidates. If you want an accommodation/adjustment for a disability or any other reason during the hiring process, please send a request to your recruiting partner.

We are an equal-opportunity employer and celebrate diversity, recognizing that diversity builds stronger teams. We approach diversity and inclusion seriously and thoughtfully. We do not discriminate on the basis of race, religion, color, ancestry, national origin, caste, sex, sexual orientation, gender, gender identity or expression, age, disability, medical condition, pregnancy, genetic makeup, marital status, or military service.