Fullstack Software Engineer (Email Security & Anti-Abuse)

**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 500+ 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 [here](https://proton.me/community/open-source)! **Purpose of the role** MSA is a highly multi-disciplinary group started in 2019 to tackle difficult mail delivery, spam, abuse, and account security problems that impact the Proton ecosystem. We built sophisticated systems from scratch that combine human intelligence and machine learning to make tens of millions of realtime or asynchronous decisions each day. Our custom systems have reduced spam filter misclassifications by over 60%, blocked millions of abusive bulk signups, protected hundreds of thousands of users from account compromise by attackers, and mitigated hundreds of DDoS attacks. In the last few years, we have also been building complicated new products, including launching Wallet, Lumo AI, and Meet. We are the main group at Proton working on AI. In order to move fast with limited resources, we are organized into autonomous teams responsible for the whole system, with expertise across infrastructure, data storage, backend, web and mobile apps, machine learning, security and operational excellence. We are looking for humble, mission-driven, systems-thinking people who want to make a big impact in a startup environment. # **What you will do** MSA builds and operates many services responsible for different domains. You will: - work with other engineers and analysts to design, build, and operate these systems - work on special user-facing features involving frontend and backend software development - You will have the opportunity to play Product or Project Managers roles and lead the whole planning and development process - be responsible for the operational excellence of the systems/features and their interaction with other systems - You may work on MSA's custom systems written in Python or on the main Proton API written in PHP or on Proton Web apps written in React or even on native iOS and Android mobile apps **Job requirements** - Deep experience with backend development (Python, PHP, or Go) - Experience with frontend design and development (JavaScript, React, Typescript, or jQuery) - Experience building complex production systems - Experience with data processing and storage (MySQL, MongoDB, Redis, Kafka, Elastic, Ceph, ClickHouse) - Able to work autonomously and lead the whole development process, from design to QA - Experience with AI tools and AI agents - Excellent English communications, both written and spoken Bonus points for: - experience with machine learning and real-time prediction systems - experience with iOS or Android app development - experience with managing Linux servers, including infrastructure as code (Puppet, Ansible) and containerization **What We Offer** - **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. Read more about our impact [here](https://proton.me/about/impact). **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 [Service Privacy Policy.](https://www.greenhouse.com/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 . *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*[*our privacy policy page*](https://boards.eu.greenhouse.io/protongdpr)*.* #LI-ONSITE