Senior Windows Engineer

Senior Windows Engineer (Drive) – Proton Join Proton and build a better internet where privacy is the default. At Proton, we believe that privacy is a fundamental human right and the cornerstone of democracy. Since our inception in 2014, founded by a team of scientists from CERN, we have dedicated ourselves to providing free and open‑source technology to millions worldwide, ensuring access to privacy, security, and freedom online. Our journey began with Proton Mail, the largest secure email service globally, and has since expanded to include Proton VPN, Proton Calendar, Proton Drive, and Proton Pass. These tools empower individuals and organizations to take control of their personal data, break away from Big Tech’s invasive practices, and defeat censorship. Our work impacts hundreds of millions of lives, from activists on the front lines defending freedom to leaders in governments protecting sensitive information. In some cases, Proton’s services have even been instrumental in saving lives by enabling secure and private communications in high‑risk situations. Proton today supports over 100 million user accounts with a growing team of over 500 people from more than 50 countries, drawn from the world’s top companies and universities. We value intelligence, learning potential, and ambition in our hiring process. Adaptability is key as we navigate uncharted territories and redefine how business is conducted online. We believe smaller teams of exceptional talent will always prevail over larger teams with lower talent density. Proton has become profitable and reached scale without relying upon VC funding, largely due to superior talent that allows us to do things faster, more creatively, and more efficiently. We have a global mindset and big ambitions but remain a start‑up at heart. We value empowerment and flexibility and keep our structure flat to keep moving fast and avoid unnecessary politics. Tired of blending into the crowd? Join us and do work you can truly be proud of. Check our social media pages to learn more about us: Twitter, Reddit, Instagram. The Role You will be responsible for designing, building, maintaining and evolving Proton applications on Windows. This includes not only building the application internals (managing and syncing local and remote state, performing cryptographic operations, etc.) but also helping us to build a resilient, scalable application (graceful degradation; log and metrics streams free of personally identifiable information). You will be involved in the entire application lifecycle, including Gitlab configuration, deployments, monitoring and alerting, and operational incident response. While this position is not a "full‑stack" position, you will be expected to collaborate with backend engineers to drive any necessary changes and/or new features needed for the Windows experience. What You Will Do Be part of a small team working to bring a "privacy by default" solution to our clients on Windows. Develop an application that delights a wide range of users, from layperson to technical, and gives confidence that their online privacy is in good hands – while getting the complexity of end‑to‑end encryption out of the way. Invest in testing and automation to improve the team's productivity and software delivery cadence. Think critically on how to divide problems into iterations of simpler, composable solutions. Re‑evaluate the minimum scope as necessary to meet objectives on‑time. Insist on high standards for application monitoring and alerting, in order to ensure a smooth customer experience at all times. Qualifications Strong experience in .NET development Strong experience building and maintaining desktop Windows applications Strong experience with concurrent, multi‑threaded programming Working knowledge of file systems Working knowledge of Git Bachelor's or master’s degree in a relevant field of study Experience with owning and maintaining large software components Experience with gradual rollouts and metrics/monitoring/alerting frameworks Benefits Office First: Collaboration is easier and more effective in person, which is why we have offices in Geneva, Zurich, Prague, Barcelona, Paris, London, Vilnius, Skopje, and Taipei. You can also enjoy working from home up to 30% of the time, while enjoying great company during our three core days in the office. Technology: We provide all the devices and software you need to excel in your role, ensuring you have the best tools at your disposal to achieve your goals. Food: Lunch and snacks are provided by Proton every day at our offices. Transport: We will always support our employees with transport costs through subsidizing public transport, bike allowances, or parking spaces based on your office location. Stock Options: At Proton, we are all owners of the company and you get stock options when you join us. Flexible Working: You can define your own working hours as long as it works with team meetings. Learning and Development: We are committed to your professional growth. Proton offers various learning opportunities, including training programs, conferences and events, and continual learning. Employee Benefits: Comprehensive health insurance plans, competitive retirement savings options, generous vacation and leave policies, and wellness programs. Work that Matters: Proton is a community‑first organization, started with the support of a crowdfunding campaign and built with community input. To this day, Proton’s only source of revenue is user subscriptions. Over 100 million people trust and support Proton, and we put our users and community first in everything we do. 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 (Proton, we, us, or our), 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 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. Seniority Level Mid‑Senior level Employment Type Full‑time Job Function Information Technology Industries Technology, Information and Internet Location Argenteuil, Île‑de‑France, France #J-18808-Ljbffr