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LLM Research Scientist (Pre-training & Post-Training)

Remote

Undisclosed employer

Fresh
Gig
Mercor

Compensation

$100-$120/hr

Apply on Mercor

Description

We're looking for experienced machine learning researchers with hands-on experience training and improving language models end-to-end. You'll work on well-scoped empirical open-ended LLM research problems.


Responsibilities

  • Train transformer-based language models from scratch and fine-tune open-weight models.

  • Get the most out of limited data and compute.

  • Construct training corpora from raw web-scale sources.

  • Build post-training pipelines.

  • Diagnose and resolve training issues.


Requirements

We are looking for candidates with strong expertise in one or more of the following areas:

Foundation Model Pre-training

Experience with:

  • Training transformer-based language models from scratch, end-to-end.

  • Data- and compute-constrained regimes: allocating a fixed budget across model size, tokens, and epochs.

  • Diagnosing optimisation failures, convergence issues, and training instabilities.

Pre-training Data

Experience with:

  • Corpus construction from raw web crawls and other large unfiltered sources.

  • Data filtering, deduplication, quality classification, and mixture/ordering optimisation.

  • Measuring data interventions rigorously.

LLM Post-Training

Hands-on experience with one or more of:

  • Supervised fine-tuning, including building your own datasets via synthetic generation, noisy or weak supervision, and rejection sampling.

  • Preference optimisation (DPO, RLHF, RLAIF) and reward modelling / human-preference prediction.

  • Alignment fine-tuning: shaping refusal behaviour, truthfulness, and unbiased reasoning while preserving general capability.

  • Fine-tuning for narrow, verifiable domains (math, code, games, structured prediction) where outputs can be checked programmatically.

Additional Areas of Interest

Experience in any of the following is a plus:

  • Scaling laws and training-efficiency research.

  • Curriculum learning and data ordering.

  • LLM evaluation: benchmark construction, contamination control, statistically sound comparisons.

  • Reinforcement learning for language models.

  • Model alignment and AI safety.

General Qualifications

  • 3+ years of machine learning research experience (PhD research counts toward this requirement).

  • Strong experience with PyTorch, JAX, TensorFlow, or similar ML frameworks.

  • Degree from a top-100 university, experience at a FAANG or comparable AI company, or an equivalent research track record through publications or impactful open-source contributions.


Why Join

  • Work on cutting-edge foundation model research.

  • Collaborate with leading AI researchers on challenging, high-impact projects.

  • Flexible, project-based work with competitive compensation.

Commitment
Hourly

Skills & categories

Data AnalysisPyTorchLLMsMachine LearningFine-tuningFoundation ModelsTensorFlowJAXReinforcement Learning
Posted
Jul 8, 2026
Slots remaining
5
First seen
Jul 8, 2026
Last seen
Jul 9, 2026