Senior Research Scientist | Model Steering

MEET DEEPL DeepL is a global AI product and research company focused on building secure, intelligent solutions to complex business problems. Over 200,000 business customers and millions of individuals across 228 global markets today trust DeepL's Language AI platform for human-like translation, improved writing and real-time voice translation. Founded in 2017 by CEO Jaroslaw “Jarek” Kutylowski, DeepL now has around 1,000 passionate employees and is supported by world-renowned investors including Benchmark, IVP, and Index Ventures. Our goal is to become the global leader in trusted, intelligent AI technology, building products that drive better communication, foster connections, and create a meaningful impact. To achieve this, we need talented people like you to join our journey. If you’re ready to shape the future of AI and grow your career in a fast-moving, purpose-driven environment, DeepL is your next destination. WHAT SETS US APART What sets us apart is our blend of cutting-edge AI technology, meaningful work, and a culture where people truly thrive. We’re a team of innovators, researchers, and creators driven by a shared purpose to unlock human potential by making work simpler, smarter, and more connected. When we share what it’s like to work at DeepL, the reactions are overwhelmingly positive. This might be because of our technology that helps millions of people and businesses communicate and work better every day, or because of the trust, curiosity, and care that shape our culture. What we know for sure is this: being part of DeepL means joining a team dedicated to innovation, growth, and well-being. Discover more about life at DeepL onLinkedIn https://www.linkedin.com/company/deepl/,Instagram https://www.instagram.com/deepl_official/, and our Blog https://www.deepl.com/en/blog. MEET THE TEAM BEHIND THIS JOURNEY Our Language AI teams form the foundation of DeepL's success. We are a dedicated group of researchers who collaborate closely with engineers, product managers, and designers. Our mission is to build the world's leading language AI system to deliver perfect translations for the most demanding use cases. To that end, we take responsibility for the entire life cycle of the machine learning models that power our language AI products. This includes data, training, quality assurance, and operational aspects. In our highly collaborative teams, each person has the scope to drive impact across the company. YOUR RESPONSIBILITIES We are looking for a Senior Research Scientist to lead fine-tuning, post-training, model-steerability, and reinforcement learning for the next generation of DeepL's LLM-based translation models. This is a high-impact, hands-on role for a researcher who can own a major research direction, prototype rapidly, run large-scale experiments, and drive breakthroughs all the way into production. Your central focus is how we blend data and shape model behaviour after pre-training. You will fuse high-value human expert data with synthetic data, and you will lead the effort to make our translation models steerable, following custom user instructions, rules, and context. You will work with model architectures at the scale of hundreds of billions of parameters. You will: - Drive the development of translation models that are steerable conditioned on user preferences, rules and context. - Drive hands-on research and development on post-training for our core translation models: supervised fine-tuning, knowledge distillation, preference optimization, and reinforcement learning tuned to translation quality. - Build reward models and evaluator models for translation, including rubric- and reference-based grading, and investigate and mitigate reward hacking and quality-estimation failure modes. - Drive an agenda toward models that ingest multimodal content and context to increase translation quality. - Own the full lifecycle of model delivery: prototyping, ablations, training, evaluation, optimization, and production deployment, working closely with engineering to ship into real-time systems at scale. - Establish strong practices for evaluation, reproducibility, monitoring, and continuous model improvement in production. - Mentor researchers and engineers, promote hands-on collaboration, and raise the bar for model quality. QUALITIES WE LOOK FOR - Proven experience making large models steerable and instruction-following by identifying the most effective method to instill a given behavior, drawing from instruction tuning, latent space methods, steering vectors, and/or constrained encoding and decoding methods. - Deep, hands-on expertise in LLM post-training (SFT, DPO), knowledge distillation (teacher-student training), and/or reinforcement learning (RLHF/RLAIF, PPO/GSPO, and reward modeling). - Strong data-centric instincts for building synthetic-data and preference-data pipelines, LLM-as-judge generation, data curation and filtering, and rea