Site Reliability Engineer - Nix/NixOS in London

Helsing is a defence AI company. Our mission is to protect our democracies. We aim to achieve technological leadership, so that open societies can continue to make sovereign decisions and control their ethical standards. As democracies, we believe we have a special responsibility to be thoughtful about the development and deployment of powerful technologies like AI. We take this responsibility seriously. We are an ambitious and committed team of engineers, AI specialists and customer‑facing programme managers. We are looking for mission‑driven people to join our European teams – and apply their skills to solve the most complex and impactful problems. We embrace an open and transparent culture that welcomes healthy debates on the use of technology in defence, its benefits, and its ethical implications.

The role involves widely spread responsibilities including:

• Packaging software for Nix
• Setting up Nix development environments
• Configuring and administering our backend NixOS infrastructure
• Upstreaming fixes and software back to Nixpkgs

Key Skills

Note: We operate in an industry where women, as well as other minority groups, are systemically under‑represented. We encourage you to apply even if you don’t meet all the listed qualifications; ability and impact cannot be summarised in a few bullet points.

• Deep knowledge of GNU/Linux and the surrounding ecosystem
• Excellent knowledge of and experience with NixOS, either in a FOSS context or in a professional context
• Hands‑on experience with configuring and administering NixOS servers, in a professional or in a volunteer or homelabbing context
• Knowledge of network protocols, in particular the Internet protocol stack (e.g. IP, TCP, UDP, TLS, Wireguard)
• Experience with Rust development
• Experience rolling out and using metrics tooling (e.g., Prometheus, Grafana, ELK)
• Familiarity with SQL and streaming database systems
• Knowledge of application‑layer security engineering, such as OIDC or system sandboxing

Nice to Have

• Experience with CppNix, Lix or DetNix development
• Knowledge of macOS system development and the macOS ecosystem
• Experience with mitigating supply‑chain security issues
• Knowledge of container‑based and cloud‑native application architectures (e.g., Docker, Azure, AWS)
• Experience packaging Rust and NodeJS software with Nix

What we offer

• A focus on outcomes, not time‑tracking
• Competitive compensation and stock options
• Relocation support
• Social and education allowances
• Regular company events and all‑hands to bring together employees as one team across Europe
• A hands‑on onboarding program (affectionately labelled "Infraduction"), in which you will be building tooling and applications to be used across the company. This is your opportunity to learn our tech stack, explore the company, and learn how we get things done – all whilst working with other engineering teams from day one

Helsing is an equal opportunities employer. We are committed to equal employment opportunity regardless of race, religion, sexual orientation, age, marital status, disability or gender identity. Please do not submit personal data revealing racial or ethnic origin, political opinions, religious or philosophical beliefs, trade union membership, data concerning your health, or data concerning your sexual orientation.