Senior Backend Engineer (Payments) in London

The goal of the Payments team is to enable revenue generation for the entire Proton ecosystem. This comes in the form of introducing new payment methods for users to architecting our client libraries. This team has impact across all of Proton's products and is critical to the success of the business as a whole. As Proton is a global company, the Payments Team works to continuously expand the possibilities for users to pay with various payment methods, beyond just plain credit cards or PayPal. The team works in tight collaboration with the Account Team (responsible for the Proton user lifecycle), the Proton Finance team, and every single Business Unit to ensure that plans, promotions and pricing meet user expectations. The mission of the team is to empower anyone in the world who wishes to use Proton services, to become a Proton subscriber by building enticing interfaces, being able to progressively reach global markets, by providing the methods and tooling allowing users to pay, and for the Proton organization to properly measure growth, and to follow the relative financial regulations.

Tech Stack and Tools: The Payments stack depends largely on external services such as payment providers, tax-information providers, currency-conversion providers. It is critical, for the success of the service, to build with resilience. Internally our backend code is generally based on PHP/Symfony, our frontend is based on React, our mobile code is based on Kotlin (on Android) and on Swift (on iOS), with a growing shared codebase in Rust. All our client-code is open-source and GPL3. We are migrating our infrastructure to Kubernetes. Everything runs on premise in Proton's data-centres. To organize our work we use classic tools such as Jira and Confluence.

Future Plans: With payments being the backbone of any subscription business, we have ambitious plans to expand the team to cover a wide breadth of topics ranging from demystifying payment performance data across regions/products, to thinking about the holistic strategy of product catalogs, and everything in between. This particular team requires someone who is a strong generalist, who thrives with ambiguity. There's huge potential for growth no matter the domain, and the outcome for any candidate is an in-depth view into how money moves globally.

What you will do:

• Build features in all of Proton's products.
• Close interactions with products and engineers across the company.
• Build scalable software architecture through software engineering best practices.
• Optimise user experience and design.

Job requirements:

• Proven experience with back-end development.
• Expertise in building scalable, high-performance solutions.
• Proficiency with profiling techniques and performance optimization tools.
• Experience leading a team initiative from discovery to production.
• Strong understanding of SQL (MySQL preferred) and data modeling best practices.
• Familiarity with Redis or other caching technologies for performance optimization.
• Knowledge of security best practices and experience implementing secure software solutions.
• In-depth understanding of HTTP/REST, including both the development and consumption of web-based APIs.
• Solid grasp of cryptographic concepts, including key exchange, and the distinction between symmetric and asymmetric encryption.

Bonus points for:

• Experience within the payments domain.

Even if you don’t meet all the requirements listed above, but feel you could still be a great fit, please still apply.

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.
• 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. 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.
• 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.
• 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 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.

Candidate Privacy Notice: When you apply for a position, refer a candidate, or are considered for a role at Proton Technologies AG, your information is stored in Greenhouse, in accordance with their Service Privacy Policy. 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. 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.