Machine Learning Research Engineer (AI)

Location: In-office in Barcelona, Spain; candidates should be ready to work from Barcelona or move there.

Company

hirify.global develops Nextflow and the hirify.global Platform to help scientists and organizations scale complex data workflows.

What you will do

• Design and build evaluation suites for an autonomous research agent.
• Turn deployment run data into training-ready corpora.
• Post-train small open-weight models using supervised fine-tuning, preference tuning, and adapters.
• Run repeated training cycles on evolving data while managing regression and forgetting.
• Collaborate with the Founding Scientist and application engineers on the Next-Gen roadmap.
• Participate in journal clubs and apply current research in specialized model post-training.

Requirements

• Hands-on experience post-training open-weight language models with SFT and at least one preference-tuning method.
• Experience retraining models on changing data and applying replay, data mixing, adapter strategies, and evaluation gating.
• Experience building task-specific evaluation harnesses and defining metrics.
• Fluent Python skills and experience with PyTorch, Transformers, TRL, PEFT, vLLM, or equivalent tools.
• Substantive open-source contributions or fine-tuned models published on the Hugging Face Hub.
• Willingness to work in-office in Barcelona or move there.

Nice to have

• Experience in computational biology, chemistry, or pharma.
• Familiarity with Nextflow or workflow orchestration.
• Experience evaluating agentic, multi-step, tool-using systems.
• Experience with distillation or small-model specialization from frontier models.
• Publications or technical reports in post-training or continual learning.

Culture & Benefits

• Flexible working hours and an international environment with more than 25 nationalities.
• Continuous skills development, a learning and development budget of 1,000 USD per year, and a home office allowance valued at over 1,000 USD.
• 23 vacation days per year, three additional company days in December, and public holidays according to the employee's location.
• Equity, private health insurance, private life insurance, and access to the Oliva mental health app.
• Team retreats, bonding activities, and a fast-growing startup environment.