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 is a profitable company that does not rely upon VC funding, supporting over 100 million user accounts with a growing team of over 500 people from over 50 different countries, 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.

Hiring at Proton is highly selective, with less than 1% of candidates hired. We believe smaller teams of exceptional talent will always prevail over larger teams with lower talent density. You will have the opportunity to work with many of the world's top minds in their fields, ranging from former international math and science olympiad winners to chess champions.

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 open-source projects here!

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.

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

The Role: 

• We are seeking candidates with quantitative portfolio management experience and intimate knowledge of systematic strategies

Job Responsibilities (include, but not limited to the following)

• Develop systematic strategies that exploit statistically-based predictive signals associated with various market inefficiencies applied to a broad variety of asset classes including global equities and/or ETFs, futures, currencies and options
• Lead, manage and grow quantitative investment portfolio
• Contribute to broader firm research and strategic initiatives

• 2+ years’ experience in developing systematic strategies including a verifiable track record with positive PnL and Sharpe
• Strong programming skills in mainstream quant programming languages, such as Python and C++

The Book Portfolio Manager Opportunity:

• Transparent and formula-based compensation
• Opportunities to contribute to other research and strategy initiatives
• Access to WorldQuant’s alpha pool, portfolio management tools and innovative technology platforms
• Access to a deep and broad menu of datasets supported by a dedicated data team
• State-of-the-art cross asset execution led by a multi-regional trading team
• Participation in internal research conferences and forums
• Autonomy to build your own strategies along with several opportunities for collaboration and mentorship
• Access to cutting edge AI and Machine Learning efforts in financial markets

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:

1. Mail delivery and spam prevention

2. Abuse detection

3. Account security

4. 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!).

Why Join Us?

• 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

• 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. (read more about our impact here)
• A great Team: Our team is diverse, collaborative, and tight-knit with people coming from all walks of life, including many of the world’s top academic institutions and organizations, such as MIT, Harvard, Stanford, Caltech, Cambridge, and ETH.
• 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. When Proton wins, you win.
• In-Person Collaboration: Amazing things happen when passionate, smart, and purposeful people get together in the same room. With offices across Geneva, Zürich, Barcelona, London and more, you'll spend most of your time collaborating face-to-face with people who genuinely care about what they're building
• 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.

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

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!

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:

• Mail delivery and spam protection
• Abuse detection and account security
• Site reliability across Proton services
• New products such as Wallet and Lumo

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.

• Assist in maintaining the operational stability of machine learning and anti-abuse systems running 24/7
• Support deployment and maintenance of services and infrastructure under guidance from senior engineers
• Help implement and improve logging, monitoring, and alerting for production systems
• Participate in debugging and resolving production incidents with team support
• Contribute to CI/CD pipelines and deployment automation workflows
• Assist in deploying and maintaining containerized services using Docker and related tools
• Support infrastructure automation efforts through scripting and configuration management
• Document operational procedures and deployment processes
• Gradually take ownership of infrastructure components and improvements as experience grows

Job requirements:

• Experience with Linux system fundamentals (command line, systemd, troubleshooting)
• Proficiency in scripting languages (Bash and Python)
• Familiarity with Docker and containerization concepts
• Basic understanding of CI/CD pipelines and automated deployments
• Basic familiarity with databases such as MySQL or similar systems
• Experience with Git and collaborative development workflows
• Strong problem-solving mindset and ability to work and learn in a fast-paced global team
• Willingness to participate in on-call rotations after initial ramp-up
• Strong communication skills in English (written and verbal)

• Hands-on experience with Ansible, Puppet, or similar configuration management tools
• Familiarity with data processing and workflow orchestration tools (Airflow, Dask)
• Experience deploying services to production environments (personal projects count)
• Exposure to monitoring and observability tools (Prometheus, Grafana, ELK)
• Basic understanding of machine learning workflows or data pipelines
• Familiarity with Terraform, Kubernetes, or cloud infrastructure platforms

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. (read more about our impact here)
• A great Team: Our team is diverse, collaborative, and tight-knit with people coming from all walks of life, including many of the world’s top academic institutions and organizations, such as MIT, Harvard, Stanford, Caltech, Cambridge, and ETH.
• 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. When Proton wins, you win.
• In-Person Collaboration: Amazing things happen when passionate, smart, and purposeful people get together in the same room. With offices across Geneva, Zürich, Barcelona, London and more, you'll spend most of your time collaborating face-to-face with people who genuinely care about what they're building
• 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.

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

Programme duration: From 4-6 months, starting in 2026. Most individuals join in April, May, or June of each year.    

Who qualifies: Penultimate or final year students completing a Bachelor's or a Master's degree. 

Qube Research & Technologies (QRT) is a global quantitative and systematic investment manager, operating in all liquid asset classes across the world. We are a technology and data driven group implementing a scientific approach to investing. Combining data, research, technology, and trading expertise has shaped our collaborative mindset which enables us to solve the most complex challenges. QRT’s culture of innovation continuously drives our ambition to deliver high quality returns for our investors.  

Over the years, QRT has invested in a global research and execution platform which has been deployed to cover all geographies and asset classes. This platform covers a broad spectrum from high to low frequency trading systems. We thrive at the intersection of cutting-edge technology, smart automation, and scalable processes, enabling us to move fast, think big, and deliver at scale.   

We are committed to identifying and developing exceptional talent, and are inviting a new cohort of outstanding individuals to join us in the year ahead. Our internship offers a stimulating, intellectually rigorous, and high-performance environment, where collaboration is key to success. You will work alongside and be mentored by industry-leading professionals, gaining invaluable experience and positioning yourself for the opportunity to secure a full-time graduate role upon successful completion of the program. 

 Your future role at QRT   

Throughout the recruitment process, we will work to align your skills, interests, and potential with the teams where you can make the greatest impact. 

As a Quantitative Research Intern, you could contribute in one of two complementary areas within one of QRT's systematic teams - spanning high, mid, and low-frequencies: 

Research 

Your core objective will be to develop high-quality predictive signals. You will leverage access to vast and diverse datasets to identify hidden statistical patterns and market opportunities. Collaborating with fellow researchers to exchange ideas and refine methodologies. You will be trained to lead the full research cycle - from idea generation to implementation.   

Trading 

You will contribute to the live deployment of QRT’s research by working on the systematic trading platform itself. This involves monitoring signal behaviour, tracking performance, and improving execution efficiency, while also helping to identify and manage potential risks. Working closely with senior Researchers and Traders, you will focus on refining and scaling systematic processes, applying your quantitative and programming skills to ensure strategies perform optimally in production. 

We’re looking for interns who are curious, creative, and collaborative. If you’re passionate about learning, excited to take on challenges, and ready to make a real impact, you’ll find plenty of opportunities to grow with us. 

Your present skillset   

• Pursuing an advanced degree in a quantitative field such as data science, statistics, mathematics, physics, or engineering   

• High level of technical knowledge in statistics, machine learning, NLP or AI techniques is a plus   

• Coding skills required in at least one leading programming language (Python and C++ or C#)  

• Experience in exploring large datasets across multiple time frames is a plus  

• Capacity to multi-task in a fast-paced environment while keeping strong attention to detail   

• Ability to work autonomously, in a collegial and collaborative setting, and with colleagues from diverse backgrounds and areas of expertise.  

• Excellent communication skills  

• Fluent in English, any other language is a plus  

Interviewing:   

• Apply online: applications are evaluated on a rolling basis by a member of our Talent Acquisition team. This is a great opportunity to stand out, as we read every application carefully and look for specific, thoughtful answers that reflect your genuine interests. 

• Interviews conducted on-site or through Teams allow us to evaluate your technical abilities and how well you align with our company culture.   

We encourage you to take part in one of our Data Challenges, which offer a valuable opportunity to engage with the types of problems encountered in the Quantitative Research role while showcasing your analytical and technical skills. Strong performance may lead to direct follow-up from our team, making it an excellent way to gain early visibility in the recruitment process: Challenge data (ens.fr)  

QRT is an equal opportunity employer. We welcome diversity as essential to our success. QRT empowers employees to work openly and respectfully to achieve collective success. In addition to professional achievement, we are offering initiatives and programs to enable employees achieve a healthy work-life balance