Senior ML Engineer (AI)

Location: Barcelona, Spain; hybrid model with required attendance at the Barcelona office 3 days per week.

Company

Product Madness, part of hirify.global, develops mobile gaming experiences using data, machine learning, and AI to personalize player experiences and support business decisions.

What you will do

• Build, train, evaluate, optimize, and maintain production ML models for prediction, recommendation, personalization, and decision support.
• Develop LLM-powered applications, RAG systems, structured-output workflows, tool-calling solutions, and agentic workflows.
• Translate ML/AI requirements into maintainable software components, services, and APIs with reliable performance and scalability.
• Design evaluation approaches, validate model quality, identify failure modes, and ensure robustness, safety, and reliability of ML/AI outputs.
• Deploy, monitor, and maintain ML/AI solutions with MLOps Engineers; optimize inference speed, latency, resource utilization, and scalability.
• Collaborate with Data Scientists, MLOps Engineers, Data Engineers, and product partners; contribute to architecture discussions, mentoring, documentation, testing, and engineering standards.

Requirements

• Expert-level Python programming, software development, automated testing, debugging, version control, and collaborative development experience.
• Hands-on experience developing, training, evaluating, and optimizing supervised learning models using scikit-learn, PyTorch, TensorFlow, or similar frameworks.
• Practical experience building LLM applications, including prompt design, structured outputs, RAG, tool calling, and agentic workflows.
• Experience creating ML/AI evaluation pipelines, measuring model performance, identifying failure modes, and validating AI outputs.
• Hands-on experience in at least one ML specialization: recommender systems, reinforcement learning, time-series modeling, unsupervised learning, or causal/Bayesian modeling.
• Experience in at least one AI domain, such as LLM/NLP applications, agentic workflows, or computer vision.
• Strong SQL skills, experience integrating data through APIs and other interfaces, and understanding of data quality and preprocessing.
• Experience with model deployment, inference services, monitoring, model versioning, and ML lifecycle management.
• Understanding of cloud platforms such as GCP, AWS, or Azure, containers, CI/CD pipelines, ML development environments, and performance optimization.

Culture & Benefits

• Hybrid working model requiring attendance at the Barcelona office 3 days per week.
• Collaborative environment involving Data Science, MLOps, Data Engineering, and product teams.
• Opportunities to mentor less experienced engineers and improve development standards and engineering practices.
• Compensation and benefits may include annual bonuses and incentives, health and wellbeing benefits, paid time off, retirement plans, insurance coverage, and local or statutory benefits, depending on role and location.
• Specific compensation and benefits details are discussed during the recruitment process.

Hiring process

• Submit a CV in English.
• Final requirements and hiring decisions remain subject to human review and approval by hirify.global.