Machine Learning Engineer in United Kingdom

About the Role

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.

Who We're Looking For

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.