Senior Backend Engineer (Innovate)

Yubo

WHO WE ARE Yubo is the Social Discovery app to make new friends and hang out online. By eliminating likes and follows, we empower our users to create genuine connections and show up as their true selves. We've pioneered a new way for Gen Z to socialize online, and with millions of active users, our goal is to redefine how we connect today and tomorrow. Our team is international, multicultural and deeply committed to its mission. As the leading platform to socialize online, we have a special responsibility to build a safe digital space for our community. Safety is embedded in our DNA, and our proactive approach focuses on user protection, support, and education. We also work closely with the broader technology industry to share our knowledge and NGOs create industry-leading child protection standards. Join us in this exciting journey and help us shape the future of social interactions! ABOUT THIS ROLE As Yubo continues to scale, Machine Learning is becoming a core production layer, powering critical systems across safety, recommendations, and product optimization. What makes this role unique is both the scale and diversity of our data, and the level of maturity we are aiming to reach. We process massive volumes of images, text, and real-time user interactions, across millions of users worldwide, creating a wide range of high-impact ML challenges, including: * Content moderation (image, text, behavior) * Recommendation systems and user engagement optimization * Behavioral detection and trust & safety models * Emerging use cases such as dynamic pricing and growth optimization At the same time, our current ML stack is still evolving. Legacy models are not fully integrated into pipelines, lifecycle management remains inconsistent, and our approach can sometimes resemble "develop, deploy, and forget." As ML usage expands across the company, this creates increasing complexity and dependency on reliable, well-structured systems. There is still a huge amount of untapped potential, with many ML use cases yet to be designed, tested, and scaled. Unlocking it requires continuously improving the reliability, scalability, and maturity of our ML systems and workflows. We are therefore looking for a Senior ML Engineer to join our Platform Engineering team, reporting directly to Mikael (Head of Platform Engineering). You will play a key role in delivering ML initiatives across the company, helping turn promising ideas into reliable production systems. You'll work on everything from model development and experimentation to deployment, monitoring, and continuous improvement, while contributing to the evolution of our ML platform and engineering practices. YOUR RESPONSIBILITIES ML SYSTEMS & DELIVERY * Deliver end-to-end ML use cases (recommendation systems, safety algorithms, moderation models, etc.). * Design, train, evaluate, and deploy ML models where appropriate. * Balance speed of delivery with robustness and reliability. ML LIFECYCLE & RELIABILITY * Drive improvements across the ML lifecycle (training, deployment, monitoring, iteration). * Establish KPIs and monitoring standards to track model performance over time. * Ensure continuous alignment with product and safety objectives. * Help improve the reliability and observability of production ML systems. PLATFORM & STANDARDIZATION * Contribute to the evolution of our ML platform through tools, workflows, and reusable components. * Help establish and promote scalable ML engineering practices across teams. * Contribute to improving self-service ML capabilities where relevant. LEGACY & ADVANCED USE CASES * Take ownership of legacy models and realign them with current business needs. * Improve, retrain, and integrate them into modern pipelines. * Contribute to best practices around LLM usage in moderation, recommendation, and other product domains. * Explore and implement advanced ML approaches where relevant. CROSS-FUNCTIONAL COLLABORATION * Partner with Data Engineering, MLOps, Backend Platform, and Product teams. * Act as a bridge between ML, platform, and business stakeholders. * Provide technical leadership on ML initiatives and help improve engineering practices across teams. * Share knowledge and help raise the overall ML maturity of the organization. OUR TECHNICAL ENVIRONMENT / ML SCOPE * ML frameworks: PyTorch * Languages: Python (data stack) * Core topics: Neural networks, LLMs, data sampling * Use cases: Recommendation systems, safety algorithms, moderation * Ecosystem: Data Engineering, MLOps pipelines, Backend Platform WHO YOU ARE * You have 5+ years of experience in ML / Data, including work on large-scale datasets (datasets of hundreds of gigabytes). * You have strong expertise in modern ML frameworks (TensorFlow or PyTorch or JAX). * You are highly proficient in Python (data ecosystem). * You have strong knowledge of neural networks and practical experience with LLM-based systems. * You understand ML systems end-to-end (data → training → deployment → monitoring). * You have strong experience in production ML systems, not only research. * You demonstrate strong product sense and can align models with business needs. * You are pragmatic and impact-driven, balancing experimentation with delivery. * You are able to explain complex ML topics clearly (strong pedagogy). * You operate well under ambiguity and can structure complex problems. * You are able to drive technical decisions and influence stakeholders through expertise and collaboration. IN YOUR FIRST 6 MONTHS, YOU WILL * Deliver an end-to-end ML use case to validate impact and execution. * Audit and improve lifecycle management of existing ML models. * Refactor and retrain at least one legacy safety model. * Build reusable ML components that improve development efficiency across teams. * Improve monitoring and observability of production ML systems. * Contribute to the evolution of our ML platform and engineering practices. * Help move critical ML systems toward more reliable and measurable long-term operation. THE RECRUITMENT PROCESS * Phone screen with a Talent Acquisition Manager * Interview with Mikael (Platform Engineering Director) * Technical case study * Cultural fit assessments WHAT WE OFFER * A highly competitive salary range as well as equity in the company * A highly flexible remote work policy, 2 days at the office per month, with monthly team events. * We also cover fees for external professional events and meetups (Android Makers, etc…) * Great health insurance coverage for both you and your family by Alan, fully paid for by Yubo ! * Numerous benefits for parents: additional parental leave, easy access to nurseries and daycare facilities in France. OUR APPROACH TO PRIVACY & SAFETY As part of your role, you may handle tools and features involving personal data. We expect all employees to demonstrate strong awareness of privacy and safety issues, and to actively support our Privacy & Safety by Design efforts. Join Yubo and help shape the future of Social Discovery while enjoying a culture that values flexibility, well-being, and impact.   Here’s how we live our mission every day: You own the impact: Step up, adapt, and make it matter Unconventionally Smart: Hack with intent, borrow smart, build better Be Bold & Resilient: Raise your head, break barriers, keep moving forward One team, one mission: No egos, no passengers, just shared wins   Trust & Flexibility: Our hybrid model calls for only two office days a month; the rest is up to the rhythm that works best for you.   Enjoy Top-notch Benefits Culture is central at Yubo, hence the numerous benefits: Cool Workplace: enjoy our amazing Parisian office and our many hybrid work options Team Activities: participate in get-togethers, events, and team-building activities Family-Friendly: we support parents with childcare options and family-friendly policies Wellness Programs: benefit from comprehensive health insurance, wellness programs, sports classes, and mental well-being initiatives

Yubo

WHO WE ARE Yubo is the Social Discovery app to make new friends and hang out online. By eliminating likes and follows, we empower our users to create genuine connections and show up as their true selves. We've pioneered a new way for Gen Z to socialize online, and with millions of active users, our goal is to redefine how we connect today and tomorrow. Our team is international, multicultural and deeply committed to its mission. As the leading platform to socialize online, we have a special responsibility to build a safe digital space for our community. Safety is embedded in our DNA, and our proactive approach focuses on user protection, support, and education. We also work closely with the broader technology industry to share our knowledge and NGOs create industry-leading child protection standards. Join us in this exciting journey and help us shape the future of social interactions! ABOUT THIS ROLE At Yubo, Product Managers don't just manage roadmaps. They help define how millions of people discover, connect, and meet new people without the pressure: no expectations, no predefined outcomes, just the freedom to explore new connections online. We're looking for a Senior Product Manager to join our Product team and help shape the future of Social Discovery. Someone who can identify opportunities, create clarity in ambiguity, and turn insights into measurable impact. You'll join one of our product squads and take ownership of a strategic product area. This could mean improving recommendations, exploring new product experiences, scaling monetization, strengthening safety, or leveraging AI to unlock new ways for people to discover, connect, and meet others. What makes this role particularly exciting is the combination of scale, complexity, and impact. Millions of people use Yubo, and every conversation, livestream, friendship, purchase and interaction generates signal at scale. You'll work with Engineering, Design, Data, Safety, Marketing and Machine Learning to turn those signals into better experiences. This role is ideal for someone who enjoys balancing strategic thinking with hands-on execution, and who wants to have a direct impact on engagement, retention, recommendation quality, safety, monetization, and the future of Social Discovery. Like what you're reading already? I think you'll enjoy what follows. YOUR RESPONSIBILITIES * Define a clear product strategy for your squad and translate company objectives into measurable outcomes * Own your squad roadmap and continuously prioritize the highest-impact opportunities for users and the business * Lead Discovery & Experimentation: Use user insights, data, and market signals to identify opportunities, run experiments, measure impact, and inform product decisions. * Partner closely with Engineering, Design, Data, Machine Learning, Marketing, Operations, and Trust & Safety teams * Drive product initiatives end-to-end, from problem framing and discovery to launch and post-release analysis * Balance user experience, business objectives, technical constraints, and long-term platform health * Create alignment across stakeholders and lead without direct authority through clear communication and structured decision-making * Continuously improve how your squad operates, learns, and delivers value TOOLS WE USE * Amplitude, SQL, Looker * Figma * Notion * Slack * Enterpret * AI tooling: Claude Code, ChatGPT Codex, Dust WHO YOU ARE * You have 5+ years of experience as a Product Manager, ideally in a startup or scale-up environment * You have worked on consumer, social, mobile, gaming, marketplace, or subscription-based products * You have strong product strategy and roadmap ownership experience * You have the conviction to defend a strong product point of view and make bold calls * You are comfortable moving between discovery, execution, analytics, and stakeholder management * You know how to define meaningful success metrics and evaluate product performance through data * You have experience collaborating closely with Data, Machine Learning, and Engineering teams * You have strong product intuition combined with analytical rigor * You are comfortable making decisions with imperfect information * You communicate clearly and know how to align stakeholders around difficult trade-offs * You know how to balance user value and business outcomes * You're excited by fast-moving environments where priorities evolve and opportunities emerge quickly WITHIN A MONTH, YOU WILL * Get familiar with Yubo's product, users, business model, and company objectives * Build strong relationships with your squad and key stakeholders across Product, Engineering, Design, Data, ML, and Leadership * Understand the main product metrics, experimentation framework, and current roadmap * Learn how Yubo combines user insights, research, and analytics to drive product decisions * Start contributing to product discussions and discovery work WITHIN 6 MONTHS, YOU WILL * Own your squad's roadmap and key initiatives from discovery to delivery * Launch experiments that generate measurable impact on your squad's objectives * Improve one or more key product outcomes such as retention, engagement, recommendation quality, monetization, or trust * Build strong cross-functional relationships and become a trusted partner for your squad * Establish yourself as a key contributor to product strategy and decision-making across your domain * Help raise the bar on product thinking, experimentation, and execution across the Product organization THE RECRUITMENT PROCESS * Phone screen with Anita, Talent Acquisition * First interview with Sacha, our CEO * Product case study and debrief with Product Managers * Cultural fit assessments * And if everything went well, an offer! WHAT WE OFFER * A highly competitive salary range as well as equity in the company * A highly flexible remote work policy, 2 days at the office per month, with monthly team events. * We also cover fees for external professional events and meetups (Android Makers, etc…) * Great health insurance coverage for both you and your family by Alan, fully paid for by Yubo ! * Numerous benefits for parents: additional parental leave, easy access to nurseries and daycare facilities in France. OUR APPROACH TO PRIVACY & SAFETY As part of your role, you may handle tools and features involving personal data. We expect all employees to demonstrate strong awareness of privacy and safety issues, and to actively support our Privacy & Safety by Design efforts. Join Yubo and help shape the future of Social Discovery while enjoying a culture that values flexibility, well-being, and impact. Here’s how we live our mission every day: You own the impact: Step up, adapt, and make it matter Unconventionally Smart: Hack with intent, borrow smart, build better Be Bold & Resilient: Raise your head, break barriers, keep moving forward One team, one mission: No egos, no passengers, just shared wins   Trust & Flexibility: Our hybrid model calls for only two office days a month; the rest is up to the rhythm that works best for you.   Enjoy Top-notch Benefits Culture is central at Yubo, hence the numerous benefits: Cool Workplace: enjoy our amazing Parisian office and our many hybrid work options Team Activities: participate in get-togethers, events, and team-building activities Family-Friendly: we support parents with childcare options and family-friendly policies Wellness Programs: benefit from comprehensive health insurance, wellness programs, sports classes, and mental well-being initiatives

AMBOSS

Hi! We are AMBOSS and we are looking for a Senior Backend Engineer who is passionate about robust system architecture but also eager and willing to dive into the frontend when needed. Join our team and shape the future of medical education with us! About AMBOSS AMBOSS is a dynamic learning and clinical decision support tool committed to empowering medical professionals globally to deliver optimal care. Since our inception in 2012, we've harnessed cutting-edge technology to transform the way physicians acquire and apply scientific knowledge. Each AMBOSSian is passionate about being the champion of clinicians today - this motivates and unites us each day towards success. And what does success look like? When a clinician or med student tells us, “AMBOSS makes practicing medicine easier and enjoyable. I love what I do, and a big part is because of AMBOSS.” Want to learn more about our culture? Watch our video to explore what makes us unique. Why can this position be exciting for you? As a Senior Backend Engineer in the Shop Team, you will sit at the heart of our mission, building and scaling the gateway that allows medical students and clinicians around the world to access the AMBOSS platform. In this team, your backend architectural decisions have a direct, measurable impact on revenue and user discovery. Whether you are scaling high-availability payment services or prototyping a bold new hypothesis, you will be defining how the world buys AMBOSS. While your primary expertise and core focus will be on the backend, you will also have the opportunity to expand your skill set and collaborate on our frontend application, bringing a willingness to learn and work across the full stack. You will: * Ramp Up: Become a domain expert in AMBOSS's shop and payment architecture, from deep subscription logic to international tax compliance. * Build & Scale: Design, evolve, and maintain high-availability backend services handling global payment processing and complex financial transactions. * Own the Lifecycle: Manage backend discovery, technical design, deployment, monitoring, and database management at scale. * Collaborate & Learn: Build deep working relationships with Product, Design, and Finance stakeholders. Work closely with frontend engineers and proactively learn/contribute to our React-based customer-facing application when features require end-to-end implementation. * Ship Impact: Deliver end-to-end features and backend improvements from discovery to deployment, ensuring a localized, frictionless checkout experience for our global users. * Innovate with AI: Use tools like Cursor or Copilot and research how emerging technologies (LLMs, automation) can add genuine user value. You Bring: * Go (Golang): Deep, senior-level backend fundamentals (concurrency patterns, performance tuning, robust API design, and error handling). * Frontend Willingness to Learn: A foundational understanding of modern JavaScript/TypeScript and web mechanics, paired with an open, enthusiastic mindset to learn, read, and write frontend code in React alongside our team. * API Design: Comprehensive experience building scalable, clean APIs with GraphQL and/or REST. * Architectural Intuition: The ability to deconstruct complex, monolithic codebases and design highly resilient, distributed data models at scale. * Ops & Observability: Hands-on experience with Docker, CI/CD pipelines, and cloud infrastructure (AWS/Kubernetes). You write comprehensive backend tests and aggressively monitor your own metrics and dashboards. * Product-Minded & Pragmatic: You care deeply about why we build, focusing on business value and user impact over technical complexity for its own sake. You know when to ship a quick proof-of-concept and when to invest in long-term stability. * AI-Native & Comfort with Ambiguity: You are excited by AI-assisted development and can make sound technical decisions even when requirements are still evolving. Nice to Haves * Payment Systems Knowledge: Strong conceptual understanding or direct hands-on experience building, scaling, or maintaining payment flows and subscription infrastructure (e.g., Stripe, Adyen, Braintree). * PHP: Familiarity or previous engineering experience with PHP, as it helps navigate components of our ecosystem. * Exposure to Event-driven architectures, message queues (e.g., Kafka, RabbitMQ), or distributed tracing. * Previous work with LLM integration or AI-powered features. Benefits: 🌴 Rest & Time Off (30 paid vacation days, AMBOSS holiday, personal purpose day and more) 🥙Food & Office Comfort (Daily healthy breakfast & lunch by in-house chef in Berlin HQ, AMBOSS daycare, work remotely from other office spaces in Cologne, Sardinia, Cape Town) 🏃 Health, Fitness & Mobility (Urban Sports Club -M plan- , Fitbit Versa 3, Deutschland Ticket…) Check out the full list of benefits below: https://go.amboss.com/the-amboss-prescription-de We believe that diversity is a powerful driver of innovation and progress. That’s why we are committed to fostering an inclusive, respectful, and supportive environment where everyone—regardless of gender, age, ethnic or cultural background, religion, disability, sexual orientation, gender identity—is valued and given equal opportunity to thrive. We warmly welcome people of all backgrounds to help us fulfil our mission: empowering all medical professionals to provide the best possible care 🩺 Even if you don’t meet every single point in the job description, we still encourage you to apply. We’d love to hear from you!