All active MLOps roles based in Geneva.
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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!
About the role:
The MSA team (Mail Delivery, Spam, and Anti-Abuse) is a multidisciplinary group founded in 2019 to solve complex security challenges across the Proton ecosystem. We build sophisticated systems from scratch that combine human intelligence and machine learning to make tens of millions of real-time or asynchronous decisions daily. Our focus areas include:
Mail delivery and spam prevention
Abuse detection
Account security
Site reliability and resilience
Over the past few years, our custom systems have:
Reduced spam filter misclassifications by over 70%
Blocked millions of abusive bulk signups
Protected hundreds of thousands of users from account compromises
Mitigated hundreds of DDoS attacks
Recently, we’ve expanded our impact with Proton Sentinel (an AI-human hybrid security program) and Proton CAPTCHA (our own puzzle system to detect and prevent abuse). We’re now scaling our capabilities with agentic AI to enable autonomous threat detection and response.
In 5 years, we’ve grown from 2 engineers to 40+ engineers and analysts across 3 continents, operating 24/7. We’re looking for curious, collaborative, and impact-driven engineers who thrive in a startup environment and want to shape the future of secure AI.
What You Will Do
Design and deploy scalable ML systems using modern MLOps practices, including real-time inference, model monitoring, and automated retraining pipelines.
Architect agentic AI systems capable of autonomous threat detection, adaptive policy enforcement, and self-healing security responses.
Build tools for model development, debugging, and explainability to accelerate iteration and transparency.
Optimize ML workflows for distributed environments to handle large-scale data processing.
Collaborate cross-functionally with security analysts, backend/frontend engineers, and customer support to align technical solutions with user needs.
Advance the state of ML for anti abuse and account security, exploring cutting-edge techniques like adversarial robustness, graph-based anomaly detection, and privacy-preserving AI.
What You Bring
Degree in Computer Science or a related quantitative field, with 2+ years hands-on experience in building and running ML systems.
Production-level ML expertise: You’ve shipped models that handle real-world scale and complexity.
Hands-on experience with LLMs in agentic environments.
Strong software engineering skills: Proficiency in Python, with a solid understanding of backend and server fundamentals.
Statistical rigor: Deep understanding of probability, hypothesis testing, and experimental design.
Experience with adversarial ML or red-teaming ML systems.
Experience working on distributed systems.
Contributions to open-source security/privacy tools.
Knowledge of federated learning, differential privacy, or on-device inference.
Familiarity with graph-based anomaly detection or knowledge graphs.
Technical leadership: Experience owning projects, mentoring peers, and driving technical direction.
Security mindset: Familiarity with abuse patterns, adversarial attacks, or threat intelligence (bonus points!).
Impact at scale: Your work will protect millions of users globally.
Cutting-edge tech: Tackle challenges like agentic AI, real-time threat detection, and privacy-preserving ML.
Collaborative culture: Work with a global team of experts in security, ML, and systems engineering.
Growth opportunities: Lead initiatives, mentor other, and learn across a diverse technology stack
Mission-driven: Contribute to a privacy-first internet where users control their data.
What We Offer
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. 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 our privacy policy page.
#LI-ONSITE
Ready to apply?
Apply to ProtonJoin 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!
Purpose of the role:
We are looking for a MLOps / Infrastructure Engineer to join the MSA (Mail Security & Anti-abuse) team and support the operation and evolution of our machine learning anti-abuse systems.
MSA is a multidisciplinary group created in 2019 to tackle complex problems in mail delivery, spam prevention, abuse detection, and account security across the Proton ecosystem. Our systems combine human expertise and machine learning to make tens of millions of decisions daily, protecting users from spam, fraud, account compromise, and large-scale attacks.
Today, our focus areas include:
Our systems have reduced spam misclassifications by over 60%, blocked millions of abusive signups, protected hundreds of thousands of users from account compromise, and mitigated hundreds of large-scale attacks.
To move fast with limited resources, we operate as autonomous teams owning systems end-to-end across infrastructure, backend, data, ML, and operations. In just a few years, we have grown from 2 to over 60 engineers and analysts across three continents, providing 24/7 protection to millions of users.
We are looking for humble, mission-driven engineers who enjoy learning, improving systems, and making a real-world impact.
This role is ideal for someone early in their career who wants to build strong foundations in infrastructure, automation, and production ML systems. You will work closely with experienced engineers to deploy, monitor, and maintain critical services that run 24/7 and protect millions of Proton users.
What you will do:
As an MLOps / Infrastructure Engineer, you will contribute to the reliable operation and continuous improvement of systems protecting millions of Proton users.
Job requirements:
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
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. 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 our privacy policy page.
#LI-ONSITE
Ready to apply?
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