Requirements:

5+ years building and operating backend systems in production, including code you stayed responsible for long after launch, with a focus on modern PHP
Working knowledge of Rust, or clear evidence you can get there quickly — we care that you understand ownership and lifetimes
Genuine taste in API design. You have opinions about naming, defaults, error handling, and what belongs in a library versus a service
A feel for architecture at codebase scale — you have worked somewhere large enough that module boundaries and dependency direction mattered, and you have views on what keeps a monorepo healthy
Experience evolving shared code that other teams depend on, and doing it without breaking them
A security mindset. You think about how the abstraction you just wrote will be misused
The influence to get an internal library adopted rather than worked around, and the patience to carry a design through disagreement between two teams who both think they're right

Nice to Haves:

Domain-Driven Design, or similar experience modelling complex domains where the boundaries matter
Background in developer tooling, platform, or DX teams
Contributions to open source, especially libraries with real users
Experience migrating a codebase incrementally between architectures or languages
Experience with applied cryptography, key management, or end-to-end encrypted systems
Experience with building CI/CD

Design and build shared libraries, framework layers, and internal services used across every Proton product
Turn recurring patterns into good abstractions
Write documentation and examples people actually use, and treat adoption as part of shipping
Improve the day-to-day: build times, local dev setup, test ergonomics, debuggability, developer experience
Work in the open with product teams — RFCs, design reviews, and the occasional pull request into someone else's repo to show what you mean
Work closely with other developers to help integrate libraries seamlessly into applications

Work that Matters: millions of people trust Proton with their privacy. We answer only to our users — not advertisers, not investors with conflicting agendas, not governments.
Work with smart and dedicated people: Our team is diverse, collaborative, and tight-knit with people coming from all walks of life.
Technology: you'll get the right hardware and the right software you need to do your best work.
Learning & Development: we invest in your growth because sharp people make us better.
Employee Benefits: your wellbeing isn't an afterthought. We offer strong health coverage, solid retirement options, generous leave, and wellness support.
Stock Options: at Proton, we all have the opportunity to be owners of the company.
In-Person Collaboration: Amazing things happen when passionate, smart, and purposeful people get together in the same room.
Food: Lunch and snacks are on us every day in our offices.
Transport: getting to the office shouldn't cost you. We cover public transport, bike allowances, or parking.
Flexible Working: you own your schedule. Set hours that work for you and your team.