Senior Research Scientist | Model Steering in London

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.

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.

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.

Your responsibilities include:

• 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.
• Deep, hands-on expertise in LLM post-training, knowledge distillation, and/or reinforcement learning.
• Strong data-centric instincts for building synthetic-data and preference-data pipelines.
• Experience designing evaluation and reward signals using automatic metrics.
• A hands-on builder who enjoys training models, running experiments, debugging pipelines, and integrating ML systems into production.
• Ownership of a substantial research direction with strong execution, and experience mentoring others.
• Strong coding and experimentation skills (Python, PyTorch/JAX/Tensorflow).

Nice to have:

• Demonstrated experience fine-tuning and training large models at scale.
• Experience fine-tuning existing reasoning models for specific tasks and behaviors.
• Experience with machine translation, multilingual NLP, or language quality estimation.
• Familiarity with inference and serving at scale.
• Publications at top-tier venues.

What we offer:

• Diverse and internationally distributed team.
• Open communication, regular feedback.
• Hybrid work, flexible hours.
• Virtual Shares - An ownership mindset in every role.
• Regular in-person team events.
• Monthly full-day hacking sessions.
• 30 days of annual leave.
• Competitive benefits.

If this role and our mission resonate with you, but you're hesitant because you don't check all the boxes, don't let that hold you back. At DeepL, it's all about the value you bring and the growth we can foster together. Go ahead, apply—let's discover your potential together.

We are an equal opportunity employer. You are welcome at DeepL for who you are - we appreciate authenticity here. Our product is for everyone, and so is our workplace.