ML Engineer · Freelance · Madrid
Machine learning engineer in Madrid
Freelance machine learning engineer based in Madrid. I build data pipelines, train and evaluate models, serve them in production and keep them monitored. From notebook to a working system, with rigour at every step.
Engineering, not demos
The difference between a notebook and a system is the engineering in between: leakage-free validation, honest evaluation, reproducible pipeline, API with input schemas, drift monitoring and a version registry. That is what I build.
Tabular, NLP and LLMs
Gradient boosting and neural networks for tabular data, transformers and embeddings for text, and LLM-based applications when the problem calls for it. I have implemented a transformer from scratch, so I understand what is inside when something breaks.
Production as part of the design
I design the model thinking from the start about how it will be served: what input format, what decision threshold given the real business cost, how to version and how to detect when production data drifts away from training.
Remote or on-site in Madrid
I work remotely with clients across Spain, and on-site or hybrid for projects in Madrid. Available for short diagnostic projects or longer implementation contracts.
Looking for an ML engineer for your project?
Write to me with what you need: a first model, a production API, an audit. Free first call to explore the fit.
Start a projectFAQ
What does a machine learning engineer do exactly?
An ML engineer designs and builds the full system: collects and prepares data, defines the problem correctly, trains and evaluates the model, puts it in production and monitors it. It is different from a pure data scientist (more exploratory analysis) or a pure data engineer (more data infrastructure).
Do you work freelance or only for companies?
I work freelance for companies of any size: from startups that need a first model to mid-sized companies that want to strengthen their data team on a specific project. Also ad-hoc consulting for diagnosis or audit.
How much does a freelance ML engineer cost in Madrid?
The rate depends on the type of project and duration. A fixed-scope project (pipeline + model + API) is quoted at a fixed price. For longer collaborations, I work on daily or monthly rates. Call me to discuss your specific case.
What technologies do you use?
Python with scikit-learn, XGBoost and LightGBM for classical ML; PyTorch for deep learning and NLP; FastAPI and Pydantic for APIs; Docker and GitHub Actions for infrastructure; Prometheus and Grafana for monitoring. For LLMs, I work with the OpenAI API, HuggingFace models and LangChain when applicable.
Can I hire you for a short project?
Yes. I do one-week diagnostic projects (existing model audit or problem definition), 4-8 week implementation projects (pipeline + model + API) and longer collaborations. The minimum is a few days of consulting.