Senior Backend Engineer (Foundation)

Location: Barcelona or Geneva; most work involves in-person collaboration in the office

Company

Proton develops privacy-focused products including encrypted email, VPN, cloud storage, password management, and calendar services.

What you will do

• Design and build shared backend libraries, framework layers, and internal services used across Proton products.
• Turn recurring engineering patterns into reusable abstractions and support their adoption.
• Own initiatives end to end, including implementation, documentation, versioning, and migration paths.
• Improve build times, local development, testing ergonomics, debugging, and developer experience.
• Collaborate with product teams through RFCs, design reviews, and integration work.
• Help other developers integrate shared libraries into their applications safely.

Requirements

• 5+ years of experience building and operating backend systems in production, with a focus on modern PHP.
• Working knowledge of Rust or clear evidence of being able to learn ownership and lifetimes quickly.
• Strong understanding of API design, including naming, defaults, error handling, and library-versus-service boundaries.
• Experience with architecture at codebase scale, including module boundaries, dependency direction, and healthy monorepo design.
• Experience evolving shared code used by multiple teams without breaking existing consumers.
• Security-minded approach to designing abstractions and influencing adoption across teams.

Nice to have

• Domain-Driven Design or experience modelling complex domains.
• Background in developer tooling, platform, or developer experience teams.
• Open-source contributions, especially to libraries with real users.
• Experience migrating codebases between architectures or languages.
• Applied cryptography, key management, end-to-end encryption, or CI/CD experience.

Culture & Benefits

• Work focused on privacy products used by millions of people.
• Independent, profitable company with a diverse and collaborative team across 50+ countries.
• Hardware and software provided for effective work, alongside learning and development support.
• Health coverage, retirement options, generous leave, wellness support, and stock options.
• Flexible working hours with in-person collaboration in offices including Geneva, Zürich, Barcelona, and London.
• Office support including lunch, snacks, public transport, bike allowances, or parking.