[Hiring] Senior AI Research Engineer @Phrase

Role Description

Phrase's AI Research team builds, trains, and evaluates the proprietary translation models and agentic workflows that power the platform's language quality. This role takes ownership of a significant research workstream within that portfolio, extending Phrase's live systems and shaping the direction of the team's wider research. You'll work across fine-tuning and instruction-tuning LLMs for domain-specific machine translation, designing evaluation frameworks that combine automatic metrics and LLM-as-judge approaches, and building agentic workflows for multi-step reasoning and tool use.

What you'll be responsible for:

• Design, train, and evaluate LLMs for translation and language-quality tasks, using fine-tuning techniques such as LoRA and DPO and instruction-tuned models.
• Design and implement evaluation frameworks for translation quality, combining automatic metrics (BLEU, TER, ChrF, MQM, COMET), LLM-as-judge approaches, and hybrid pipelines.
• Build and evaluate agentic workflows for NLP problems, spanning multi-step reasoning, tool use, and structured output generation.
• Own a significant workstream within the team's model-development programme, from data and training through evaluation and production integration.
• Design and run reproducible experiments, documenting results and decisions clearly.
• Work with Product, Engineering, and Solutions to turn research findings into shippable capabilities.
• Benchmark frontier models — OpenAI, Gemini, Claude, and open-source — against internal baselines.
• Evolve the team's quality-evaluation systems, including style-guide integration and customer-led, outcome-oriented metrics.
• Shape decisions on active learning, feedback-loop design, and data-pipeline strategy for continuous model improvement.
• Mentor junior researchers, review PRs and research write-ups, and contribute to reading groups and deep dives.
• Contribute to hiring, including take-home review and technical interviews.
• Represent your work in cross-functional forums with Product and Engineering.

Qualifications

• Strong hands-on experience fine-tuning LLMs or large transformer-based models; familiarity with pre-training and preference-tuning (RLHF/DPO) is desirable.
• Solid NLP background, with demonstrable expertise in at least one of: machine translation, MT evaluation, information extraction, text generation, search optimization, or reinforcement learning.
• Ability to design, build, and evaluate agentic systems, including tool-calling agents, multi-agent pipelines, or LLM-orchestrated workflows.
• Experience designing and running evaluation frameworks, including automatic metrics and human-in-the-loop evaluation design.
• Strong Python skills and experience with ML/NLP libraries such as Hugging Face or PyTorch.
• Familiarity with workflow orchestration tools such as Flyte, Prefect, or Airflow (desirable).
• PhD in Computer Science, Computational Linguistics, or a related field, or an MSc with equivalent hands-on research or industry experience.
• Industry experience with production NLP systems, including shipping models, handling data pipelines, and monitoring quality in live traffic (desirable).
• Familiarity with the localization and MT domain, including MQM, COMET, post-editing workflows, segment-level quality signals, or TMS integrations (desirable).
• Experience with experiment tracking tools such as Weights & Biases, and model-serving or cloud ML infrastructure such as vLLM, TGI, AWS SageMaker, or GCP Vertex AI (desirable).
• Experience with frameworks for structured agentic pipelines such as PydanticAI or LangGraph (desirable).
• Strong publication record or open-source contributions in NLP/ML (desirable).
• Product-minded, thinking about research in terms of what it enables and who it serves, not just whether the numbers went up.
• A natural driver who identifies open problems and moves work forward without waiting to be pushed.
• Growth-oriented, motivated to expand technical scope and mentor others, with a path toward greater research leadership over time.

Requirements

• Current tech stack includes Python, Hugging Face, PyTorch, Weights & Biases, PydanticAI, LangGraph, vLLM / TGI, AWS SageMaker / GCP Vertex AI, Flyte / Prefect / Airflow.

Benefits

• Work experience in a successful and growing global SaaS company.
• Be part of an international team in Europe, APAC, and the Americas.
• Expert colleagues in their field who are determined to build the best localization platform on the market.
• An agile work environment, where it is encouraged to take smart risks.
• A culture full of trust, support, and loyalty, where respectful and open feedback is valued, and diversity is fully embraced.
• A positive, open-minded, and innovative atmosphere.
• Support in your professional development and personal career goals.

• 4 Company holidays additional to your regular holidays (1 day per quarter where the entire company is off to celebrate our achievements).
• Christmas break to allow you to spend time with family and friends without use of your vacation allocation.
• Your birthday is off because it is important to celebrate you as well.
• 2 Giveback days where you can support the local community, volunteer, and/or participate in charity events and activities.
• Professional and extensive onboarding.
• Enterprise Claude Licence.
• Additional local benefits depending on the entity you're hired at, just ask your Talent Acquisition Partner.