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 Details

Workplace: Remote (asynchronous collaboration). Employment Type: FULL_TIME. This role aligns to Madrid job-search intent for remote opportunities while operating fully online.

How To Apply

Apply through Rex.zone and include brief notes on your annotation experience (NLP, RLHF, QA evaluation, computer vision annotation, or content safety labeling) and your availability for full-time remote projects.