Machine Learning Engineer

We are looking for machine learning engineers to help train and evaluate AI models on machine learning and LLM engineering tasks. You will design tasks, review AI-generated ML code and methodology, and write the reference answers that models are measured against.

Key Responsibilities

• Design machine learning and LLM engineering tasks (data pipelines, training and evaluation code, experiment design) with reference solutions.
• Evaluate AI-generated training, evaluation and data-processing code for correctness and efficiency.
• Review experimental methodology, including data leakage, metric choice, baselines and reproducibility.
• Write reference answers and rubrics for machine learning questions at professional depth.
• Compare model outputs and give structured written feedback.
• Document recurring errors in model reasoning about ML concepts.
• Follow project guidelines, take part in calibration and review sessions, and incorporate feedback to keep quality consistent.

Required Qualifications

• Degree in computer science, statistics or a related field, or equivalent experience.
• 3+ years of machine learning engineering or applied ML experience.
• Python with PyTorch or TensorFlow; solid grounding in model training, evaluation and deployment.
• Experience building data pipelines and tracking experiments.
• Fluent written English.
• Reliable, detail-oriented, and able to work independently and meet deadlines in a remote setting.

Preferred Qualifications

• LLM fine-tuning or evaluation experience.
• Published work or strong competition results.
• Experience with distributed training or inference optimisation.
• Prior AI-training or annotation experience.

Legal and Compliance Notice

• All content you submit must be lawful, and you must have the right to share it.
• Do not submit confidential or proprietary material belonging to an employer, client or third party, or personal data without a lawful basis.
• Rex may verify identity, credentials, ownership and licensing; may reject or remove any submission; and may report unlawful submissions to the relevant authorities.
• Engagement and payment are subject to successful verification and to applicable sanctions, export-control, tax and employment laws.
• The contractor agreement will set out ownership and licence terms for the work you deliver (to be confirmed by Rex Legal).

Compensation: USD $75–150 per hour, adjusted by country of residence.