Fullstack Software Engineer; Autonomous systems

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 !

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 big data, human intelligence, machine learning, and AI agents to make tens of millions of realtime or asynchronous decisions each day. Our custom systems have reduced spam filter misclassifications by over 80% and protected millions of users from account compromise by attackers.

In order to move fast with limited resources, we are organized into autonomous teams responsible for the whole system, with fullstack expertise across infrastructure, data storage, backend, frontend, machine learning, and AI agents. We are looking for humble, mission-driven, systems-thinking people who want to make a big impact in a startup environment.

MSA builds and operates services responsible for different domains. You will:

work with other engineers and analysts to design, build, and operate these systems

work on 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 Proton API written in PHP or on Web apps written in React

Deep experience with backend development (Python, PHP, or Go)

Deep experience with using AI agents for coding

Experience building complex production systems

Experience with data processing and storage (MySQL, MongoDB, Redis, Kafka, Elastic, Ceph, Click House)

Able to work autonomously and lead the whole development process, from design to QA

Excellent English communications, both written and spoken

Experience with machine learning and real-time prediction systems

Experience with infrastructure-as-code and Kubernetes

• 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…