Senior ML Engineer (Fintech Engineering)

Location: Warsaw, Poland, with hybrid work and ideally one day per week in the Warsaw or Kraków office

Company

InPost Pay is building a large-scale fintech platform from the ground up, with a lean engineering organization in Poland and AI-native engineering at its core.

What you will do

• Build and ship credit-scoring and merchant-underwriting models for BNPL and MCA decisioning across feature engineering, training, validation, deployment, and monitoring.
• Engineer point-in-time-correct features using the shared feature store and collaborate with Data Engineering on source contracts and freshness SLAs.
• Design and operate agent loops and orchestration graphs with context, tools, evaluations, and guardrails.
• Deploy and operate models using versioning, model CI/CD, champion/challenger, and shadow-deployment practices.
• Monitor model drift, stability, and performance, then trigger retraining, recalibration, or rollback when thresholds are breached.
• Build validation and backtesting harnesses or experiment, evaluation, retraining, and promotion loops that produce audit-ready evidence.

Requirements

• End-to-end applied machine learning experience at scale, including feature engineering, training, validation, deployment, and monitoring.
• Experience with model validation methods including backtesting, PSI, Gini/KS discrimination, and calibration.
• Experience with MLOps, model versioning, CI/CD, champion/challenger or shadow deployment, drift detection, and automated alerting.
• Strong Python and SQL skills, with Spark or Databricks for large-scale model training and serving.
• Experience with feature stores, explainability techniques such as SHAP/LIME, and regulatory-defensible model documentation.
• Fluent English at B2+ level and availability for hybrid work in Poland are required.

Nice to have

• Independent model-review or validation experience.
• CCD2 and consumer-credit regulatory knowledge, MCA underwriting, merchant-risk data, or fraud-detection modelling.
• IFRS 9 provisioning, expected-credit-loss modelling, or real-time low-latency model serving experience.

Culture & Benefits

• Greenfield fintech engineering with strategic impact on AI-native ML practices.
• Modern tooling and space to experiment with AI technologies and bring them into production.
• Collaborative, fast-moving environment with autonomy and accountability.
• Hybrid work arrangement with one office day per week preferred in Warsaw or Kraków.
• B2B contract.