Software Engineer (Java/Python) - Machine Learning

Quick Facts

Role: Software Engineer working with Java/Python and Machine Learning in an e-commerce project. Work mode: remote. Rate: 125 PLN net + VAT/hour (depending on experience and scope).

Description

You will design, develop, and maintain backend applications in Java, using Python to process data and develop supervised machine learning models for predictive business solutions. The work includes building reliable models, validating them with time-series awareness, and integrating them into production Java services.

Responsibilities

• Design, develop, and maintain backend applications and data-processing components in Java/Python.
• Build, train, and optimize predictive supervised regression models (e.g., Gradient Boosting with LightGBM) using scikit-learn.
• Prepare, process, and analyze large tabular datasets using Pandas and NumPy.
• Implement feature engineering, including features for predictive models and time-series data.
• Design and run model validation for time-series characteristics, selecting appropriate metrics and assessing quality and stability.
• Compare model results with baselines and mitigate overfitting and data leakage; ensure feature consistency between training and production.
• Integrate ML models into Java-based backend applications and ensure correct production behavior.
• Collaborate on architecture to enable effective model access and reuse by business applications.
• Participate in code reviews, testing, performance optimization, and maintenance.
• Work with an international team, data analysts, and other technical specialists.

Requirements

• At least 4 years of commercial experience in a similar role.
• Very strong Java skills.
• Practical Python experience.
• Ability to write clean, readable, efficient production-ready code.
• Good understanding of Machine Learning, especially supervised learning.
• Hands-on experience building predictive models for tabular data (especially regression).
• Knowledge of Gradient Boosting and practical experience with LightGBM.
• Experience with large-scale tabular data using Pandas and NumPy.
• Practical knowledge of scikit-learn and/or LightGBM for model development and evaluation.
• Feature engineering experience for predictive and time-series data.
• Ability to design time-series-aware validation and select suitable evaluation metrics.
• Ability to compare results to baselines and address overfitting and data leakage.
• Awareness of training vs. production consistency in data preprocessing and feature calculation.
• Experience integrating ML models into Java backend applications.
• English C1 proficiency for international project communication.

Benefits

• Work across diverse projects in Software, Embedded, Data, and Cloud Services.
• Participation in additional pre-sales and expert initiatives.
• Medical care access, sports card, and cafeteria platform benefits.