Remote Data Labeling Jobs in Madrid (Fully Remote)Rex.Zone is hiring for a full-time, fully remote data labeling role focused on training-data creation and quality control for AI/ML systems. You will label and evaluate text, images, audio, and conversations used in large language model evaluation and computer vision annotation workflows, improving training data quality, annotation consistency, and model performance.
What You’ll Work On
Text labeling for NLP tasks (classification, NER, summarization) and rubric-based decision making
Prompt evaluation and LLM response scoring (helpfulness/harmlessness/honesty)
RLHF-style preference ranking and pairwise judgments
QA evaluation using checklists, sampling plans, spot checks, and gold tasks
Computer vision annotation support (bounding boxes, polygons, keypoints) as needed
Content safety labeling to ensure policy-compliant outputs
Document edge cases, track error patterns, and propose guideline/rubric improvements
Asynchronous collaboration with data ops, QA,



and project leads in a remote workflow
Required Qualifications
Mid-Senior experience in data labeling or data annotation operations
Strong attention to detail and ability to follow structured rubrics and guidelines
Familiarity with NLP concepts (classification, NER, sentiment) and LLM training pipelines
Ability to explain labeling decisions clearly and maintain consistent quality under deadlines
Preferred
Experience with RLHF, large language model evaluation, and audit-ready QA workflows
Exposure to computer vision annotation formats and inter-annotator agreement methods
Background supporting AI labs, tech startups, BPOs, or annotation vendors
Employment DetailsWorkplace: Remote (asynchronous collaboration). Employment Type: FULL_TIME. This role aligns to Madrid job-search intent for remote opportunities while operating fully online.
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📌 Remote Data Labeling Jobs In Madrid
🏢 Rex.zone
📍 Madrid