Mid/Senior AI LLM Engineer (Full Remote - Spain)

📋 Description

• Fine-tune open-weight LLMs using SFT, LoRA/QLoRA and post-training methods such as DPO and GRPO
• Diagnose model failures and turn them into experiments; decide whether the answer is better data
• Build training data and evals that directly shape what gets trained next
• Improve model behavior across personalization, consistency, tone, multilingual and group
• Ship to production and use real user behavior to guide the next iteration
• Speed up the training loop so experiments are faster, easier to compare, and more reproducible

🎯 Requirements

• Personally post-trained open-weight LLMs for a user-facing product and shipped them to production
• Worked where AI was core to the product or business, not an experimental side feature
• Fine-tuning is core to your experience
• Strong Python, PyTorch and Hugging Face, with hands-on GPU training and debugging
• Build data and evals yourself and make decisions from evidence
• Take work beyond notebooks into production

🎁 Benefits

• 4 weeks (20 working days) of PTO per year
• Annual in-person gathering
• Monthly health & wellness allowance of 100 USD for health insurance expenses
• Unlimited 1:1 sessions with psychologists and lifestyle experts through OpenUp (available to up to
• Co-working space budget up to twice per month (35 EUR / 40 USD per visit)
• Learning budget for courses, books, conferences, events, or certifications