Frontend Engineer (Lumo AI)
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, Proton Pass, Proton Wallet, and Lumo by Proton. 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 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! About Lumo Lumo is Proton's privacy-first AI assistant that fundamentally reimagines how AI should work - empowering users without exploiting their data. Unlike traditional AI platforms that harvest user conversations for training and profit, Lumo operates with zero-access encryption, keeps no server-side logs, and ensures that conversations remain completely confidential. Built by the team behind Proton Mail, Proton VPN, and backed by the nonprofit Proton Foundation, Lumo represents a paradigm shift in AI development. We believe the benefits of AI are too great to miss, but the privacy risks of current implementations are too serious to ignore. Lumo is based on open-source language models, operates from Proton's European datacenters, and provides unprecedented transparency in the AI space. Our Mission : To deliver the full power of artificial intelligence while maintaining user privacy as an uncompromising core principle. We're building an AI that only works for you, not the other way around - where your conversations remain confidential and your data stays fully under your control, never shared, sold, or stolen. Our Technology : Lumo implements multiple layers of encryption throughout the entire pipeline, from device-to-server communication through to long-term storage, creating a privacy architecture that's simply much stronger than anything else on the market. The platform runs on open-source models including Mistral's Nemo and Nvidia's OpenHands 32B, with full source code transparency. Role Summary We are seeking a passionate and skilled Frontend Engineer to join our growing Lumo AI team. You’ll work across all functions of Lumo, turning designs into responsive, fast and reliable interfaces. Your code will shape the day‑to‑day experience of users, making it smoother, clearer, and more enjoyable. Full Stack Engineering Create, evolve and sustain high‑performance features that tie together the front‑end and back‑end layers of our modern stack. Ensure every component scales smoothly and integrates cleanly. What You Will Do Turn UI mockups into production‑ready React components. Integrate those components with our backend services using TypeScript and modern data‑fetching patterns. Optimize performance so pages load instantly even on slower connections. Collaborate closely with product managers, designers and other engineers to ship features end to end. Own the quality of your work: write tests, document decisions and participate in code reviews. Spot friction in the user journey and fix it before it becomes a complaint. What we expect Strong expertise in React. Solid grasp of TypeScript and JavaScript fundamentals. Experience with state‑management and data‑fetching libraries. Ability to produce clean, maintainable code without cutting corners. Good communication skills and a willingness to give and receive honest feedback. A proactive attitude – you identify problems and solve them, not wait for direction. Nice to have Exposure to AI or large language model products. Python scripting for tooling or data tasks. Knowledge of distributed systems and observability stacks. Hands‑on experience with design tools such as Figma. Why Join Lumo You'll be joining a mission-driven team at Proton, trusted by over 100 million people worldwide and owned by the nonprofit Proton Foundation. This role offers the opportunity to shape the future of AI by building fullstack infrastructure that proves privacy, performance, and reliability aren't mutually exclusive. As a Frontend Engineer at Lumo, you'll own the complete technical stack powering privacy-first AI experiences, ensuring millions of users can rely on Lumo for their most sensitive conversations with complete confidence in both AI capabilities and privacy protection. 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) 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 .*