Fullstack Applied AI Engineer

Fullstack Applied AI Engineer (Lumo) – Proton Join Proton and build a better internet where privacy is the default. We are a profitable, VC‑free company that values intelligence, learning potential, and ambition. Our mission is to provide free and open‑source technology to over 100 million users worldwide, ensuring access to privacy, security, and freedom online. About Lumo Lumo is Proton’s privacy‑first AI assistant that reimagines how AI should work—empowering users without exploiting their data. Unlike traditional AI platforms that harvest conversations for training and profit, Lumo operates with zero‑access encryption, keeps no server‑side logs, and ensures that conversations remain completely confidential. Our Mission 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—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 to long‑term storage. 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 Fullstack Applied AI Engineer to build and maintain the complete AI infrastructure powering Lumo’s privacy‑first platform. You’ll own the full stack from database to frontend, implementing AI tool‑calling systems, privacy‑preserving search, and encrypted services while ensuring 99.9 % uptime for millions of users. What You Will Do AI Systems Development Build and maintain AI tool‑calling frameworks that enable secure integrations with external services Implement a privacy‑preserving search infrastructure that doesn’t expose user queries Develop AI model‑serving pipelines with encrypted data processing throughout Create intelligent query‑routing and result‑filtering systems optimized for AI consumption Build real‑time AI conversation APIs that maintain zero‑access encryption Fullstack Infrastructure Design high‑performance backend services in Rust for AI processing and PHP for web integration Build responsive web interfaces and admin dashboards using modern JavaScript frameworks Improve our micro‑service architecture with service mesh for scalable AI platform development Improve our automated deployment pipelines and infrastructure‑as‑code for reliable operations Develop monitoring and observability systems that preserve user privacy Site Reliability & Operations Maintain highly available AI services with automated monitoring, alerting, and incident response Implement chaos engineering and performance testing for encrypted AI workloads Build auto‑scaling systems for cost‑effective GPU utilization and global traffic handling Conduct capacity planning and optimize system performance for millions of users Core Technical Requirements 5+ years full‑stack development experience with production AI/ML systems Expert proficiency in Rust for high‑performance backend services Frontend development skills with modern JavaScript frameworks (React) Understanding of AI/ML model integration and tool‑calling architectures Experience with end‑to‑end encryption implementation and cryptographic protocols Knowledge of infrastructure automation and site reliability practices AI & Privacy Expertise Experience with large language models, AI agents, and function‑calling systems Understanding of AI model‑serving frameworks (e.g. vLLM) Knowledge of privacy‑preserving technologies and zero‑knowledge protocols Experience building search systems and information retrieval pipelines Familiarity with vector databases and semantic search technologies Infrastructure & Operations Knowledge of monitoring tools (Prometheus, Grafana) and incident response Experience with CI/CD pipelines and automated deployment systems Professional Qualities Passion for privacy rights and user‑centric AI technology Strong problem‑solving skills with attention to security and reliability Self‑motivated with ability to own complex technical challenges end‑to‑end Excellent communication skills for cross‑functional collaboration Preferred Qualifications Advanced degree in Computer Science, AI/ML, or related technical field Experience with privacy‑focused or security‑critical applications Contributions to open‑source AI, privacy, or infrastructure projects Technical Environment Backend: Rust (primary), PHP (integration) Frontend: React Infrastructure: Ansible, Docker Security: Zero‑access encryption, PGP/AES protocols Monitoring: Prometheus, Grafana, distributed tracing 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 full‑stack infrastructure that proves privacy, performance, and reliability aren’t mutually exclusive. As a Fullstack Applied AI 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. 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. 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. When you apply for a position, your information is stored in Greenhouse, in accordance with their Service Privacy Policy. 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. #J-18808-Ljbffr