LLM Data Researcher

Clera
Barcelona, Spain
On-site

Who this role is best for

Strong fit for early-career researchers with hands-on LLM post-training experience who can collaborate across teams and articulate findings to diverse audiences.

Best fit for

  • Early-career researchers with LLM post-training experience and domain evaluation skills
    — “Early-career research experience, from a PhD nearing completion to a few years post-PhD.”
  • Candidates who can translate complex findings into actionable product recommendations
    — “Turn research findings into dataset specifications and product recommendations.”
  • Individuals with a background in designing LLM evaluations or benchmarks
    — “Experience designing or building robust LLM evaluations or benchmarks.”

Things to consider

  • Relocation to Barcelona is expected if not already based there
    — “Full-time, on-site in Barcelona, Catalonia, Spain. Relocation to Barcelona is expected if you are not already based there.”
  • The role demands significant collaboration across clients, partners, and teams
    — “Collaboration across clients, partners, and the data team.”

How to stand out

  • Highlight end-to-end LLM post-training and evaluation projects in your resume
    — “Experience personally post-training and evaluating LLMs end to end”
  • Emphasize prior work with reinforcement learning and preference-based methods
    — “Select and apply training approaches, including supervised fine-tuning, reinforcement learning, and preference-based methods.”
  • Showcase publications or evaluation tooling experience if applicable
    — “Professional English; publications at leading ML or NLP venues or evaluation tooling experience are a plus.”
Pace · Fast PacedCollaboration · HighAutonomy · MediumDecision Impact · Team

Derived from job-description analysis by Serendipath's career intelligence engine.

What success looks like

  • design-and-run-evaluations-of-llms
  • turn-research-findings-into-product-recommendations
Typical background
phd-in-machine-learning-or-nlp

Skills & requirements

Required

Machine-learningNatural-language-processingReinforcement-learningLanguage-models

Preferred

Publications-at-leading-ml-or-nlp-venues

Stack & domain

Machine LearningNLPReinforcement LearningSupervised Fine-tuningReinforcement Learning From Human FeedbackReinforcement Learning From Verified RewardsReward ModelingPreference OptimizationLLM EvaluationsBenchmarksCommunicationTeamworkProblem-solvingResearchWritingAIData ScienceHealthcareFinanceLaw

About the role

Original posting from Clera via Ashby

ABOUT THE ROLE

Join the founding research team at an AI company to investigate whether expert-authored datasets improve frontier language models and inform future product direction. The role focuses primarily on hands-on experimentation, with collaboration across clients, partners, and the data team.

WHAT YOU'LL DO

  • Post-train models on curated datasets, measure performance changes, and diagnose cases where the data does not improve results.
  • Design and run evaluations of frontier language models across expert domains such as law, medicine, and finance.
  • Select and apply training approaches, including supervised fine-tuning, reinforcement learning, and preference-based methods.
  • Turn research findings into dataset specifications and product recommendations.
  • Share results through research papers, public benchmarks, and blog posts.

WHAT WE'RE LOOKING FOR

  • A PhD in machine learning or NLP, completed or near completion, or an equivalent research record.
  • Hands-on experience with reinforcement learning environments for LLMs or RL-based LLM post-training, supported by research, code, or lab or industry work.
  • Experience personally post-training and evaluating LLMs end to end, including SFT, RLHF, RLVR, reward modeling, or preference optimization.
  • Experience designing or building robust LLM evaluations or benchmarks.
  • Early-career research experience, from a PhD nearing completion to a few years post-PhD.
  • Ability to communicate technical findings to research, operations, and non-technical audiences, and fluency with AI tools and coding agents.
  • Professional English; publications at leading ML or NLP venues or evaluation tooling experience are a plus.

COMPENSATION & BENEFITS

Competitive salary, equity, and relocation support are available. Salary range and visa sponsorship details were not provided.

LOCATION

Full-time, on-site in Barcelona, Catalonia, Spain. Relocation to Barcelona is expected if you are not already based there.

Source: Clera careers (Ashby)

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