Senior Backend Engineer - Platform (Inbox)

About Proton

Join Proton and build a better internet where privacy is the default

Proton was founded in 2014 by scientists from CERN on a simple truth: privacy is a fundamental human right. Since then, we’ve built the world’s largest encrypted email service (Proton Mail) and expanded into Proton VPN, Proton Drive, Proton Pass, and Proton Calendar—tools used by millions globally to protect their freedom, fight censorship, and keep their data safe. In some situations, Proton has literally helped save lives!

We are profitable, independent (no VC control), and selectively hire from the top ~1% of applicants. Our 700+ team members across 50+ countries come from leading organizations and elite academic backgrounds. We move fast, keep hierarchy light, and prioritize impact over optics. If you want to do meaningful work with exceptionally high-caliber people, this is it. Join us and do work you can truly be proud of. Check our open-source projects !

The Team:

Our business unit, Inbox, is a cross-functional team of about 60 engineers, product managers, designers, and data analysts driving the development of Proton Mail, the company's flagship product, and Proton Calendar. Our mission is to create an end-to-end encrypted solution with a better user experience than any other productivity product on the market. It is not always an easy journey, but it is one that offers the chance to create meaningful impact and drive lasting change.

The Platform team is a subteam of Inbox, responsible for the core components reused across Mail and Calendar. Rather than owning a single feature, the team builds the shared foundations, the tooling and systems other Inbox teams build on top of, so that Mail and Calendar can scale reliably. Over the next year, the team's priority is efficiency and cost reduction.

The Platform team is partnering with the product team on new systems, such as how client apps receive updates from the server (e.g. new email and calendar event delivery), while also improving the performance of systems already in production. Quality and performance are treated as first-class concerns in everything the team ships, not an afterthought.

Purpose of the role:

As a Senior Backend Engineer on the Platform team, you'll bring hands-on experience with data-driven delivery, monitoring, and how the team plans and prioritizes its work. You'll work closely with the product team to design new systems, and with the rest of the team to improve the performance of what's already running.

What you will do:

• Architect and develop core systems: Design and build core, cross-product systems shared by Proton Mail and Calendar, with scale and cost-efficiency as first-class constraints.
• Performance: Improve the performance of existing systems, using monitoring and metrics to identify where time and infrastructure spend are going and where to cut. Drive cost-reduction and efficiency initiatives across shared platform components, from proposal to production
• Data-driven delivery: Bring a data-driven approach to technical decisions and delivery planning, shaping how the team measures and prioritizes its work
• Collaboration: Work closely with a team of backend and clients engineers, with a strong emphasis on quality and performance in everything shipped
• Testing: Develop and implement comprehensive testing strategies, including unit tests and integration tests, to ensure the reliability of core systems.

Job requirements:

• Strong experience in backend development, with a track record of designing, building and scaling systems that serve a large user base (100M+)
• Demonstrated ability to improve the performance and cost-efficiency of systems already in production
• Hands-on experience with monitoring and observability tooling (e.g. Grafana, OpenTelemetry, or equivalent), and a data-driven approach
• Solid understanding of SQL (MySQL preferred) and data modeling
• Experience leading a technical initiative end-to-end, from design through production

Bonus points for

• Experience with client-server sync or push-notification systems
• Experience with Kubernetes or other containerization technologies
• Experience with PHP/Symfony, Rust, or Python
• Full-stack experience, comfortable working across the frontend as well as the backend

What We Offer

• 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. The work you do here is real, and the impact is measurable. (read more about our impact )
• Stock Options: at Proton, we all have the opportunity to be owners of the company. From day one, you have a real stake in what we're building. When Proton wins, you win.
• 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. Proton is one of the fastest ways to accelerate your career because you'll be thrown into real challenges, with real ownership, from day one.
• Employee Benefits: your wellbeing isn't an afterthought. We offer strong health coverage, solid retirement options, generous leave, and wellness support so you can bring your best self to work every day
• In-Person Collaboration: Amazing things happen when passionate, smart, and purposeful people get together in the same room. With offices across Geneva, Zürich, Barcelona, London and more, you'll spend most of your time collaborating face-to-face with people who genuinely care about what they're building
• Food: Lunch and snacks are on us every day in our offices so you can focus on the work and not on what's for lunch.
• Transport: getting to the office shouldn't cost you. We cover public transport, bike allowances, or parking, whichever works for you.
• Flexible Working: you own your schedule. Set hours that work for you and your team — because outcomes matter more than when the clock says you started.

Our Commitment to Diversity and Inclusion

At Proton, we believe diversity drives innovation and strengthens our mission to provide privacy as a default for all. We are committed to fostering an inclusive environment where all individuals, regardless of race, ethnicity, gender, age, sexual orientation, physical ability, or socio-economic background, feel valued and empowered. We strive to create equal opportunities, promote open dialogue, and support continuous learning to ensure every voice is heard and respected.

If you need any extra support or reasonable adjustments during the hiring process, please let your talent partner know.

Candidate Privacy Notice

When you apply for a position, refer a candidate, or are considered for a role at Proton Technologies AG (Proton, we, us, or our), your information is stored in Greenhouse, in accordance with their This information is used to evaluate your suitability for the posted position. We also retain this information for consideration for future roles that you may apply for or that we believe may align with your background and skills.

If we no longer have a legitimate business need to process your information, we will either delete or anonymize it. Should you have any inquiries about how we use or manage your information, or if you wish to access, correct, or delete your data, please contact our privacy team at careers@proton.ch.

Proton does not accept unsolicited resumes from any sources other than directly from candidates. We will not pay a fee for any placement resulting from an unsolicited offer, even if the candidate is subsequently hired by Proton.

To learn more about our privacy policy, please visit .

Compensation range

• Paris : 54,000€ - 83,000€ gross annually*
• Other locations: Compensation will be discussed during the interview process
  Final compensation will be determined based on the candidate's qualifications, skills, and previous experience

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