Senior Python Developer (Data Engineering)

Quick Facts

• Role: Senior Python Developer (Data Engineering)

• Work mode: Hybrid (2 days/week in Warsaw)

• Language: English B2/C1

• Project: Long-term (initial 3-month contract with option to extend)

Description

You will join a new 5–6 person team in Poland that will take full technical responsibility for a critical multi-cloud banking system handling securities settlement and revenue management.

The work focuses on developing and optimizing Python-driven ETL/ELT processes and scalable high-volume data processing modules (revenue management and stock reconciliation).

You will also maintain production systems, profile performance, and resolve incidents through independent troubleshooting.

Responsibilities

• Develop and enhance critical banking application modules (revenue management, stock reconciliation) in a multi-cloud environment (AWS and GCP)

• Create, expand, and optimize efficient ETL/ELT processes

• Write clean, scalable, high-volume data-oriented Python code

• Maintain production systems; profile performance; independently diagnose and resolve incidents

• Analyze data architecture and resolve issues in distributed database environments

• Contribute to building a local center of expertise and collaborate closely with an international team

Requirements

• Minimum 5 years of commercial experience as a Python Developer, Data Engineer, Analytics Engineer, or similar

• Very strong Python skills for data processing applications

• Hands-on experience with Pandas and Polars for large-scale transformations and analysis

• Experience handling very large data volumes (terabytes of data, billions of records)

• Solid SQL knowledge and PostgreSQL experience, including query optimization, large tables, and partitioning

• Ability to write optimized, safe, performant code with attention to memory and CPU usage

• Ability to independently diagnose and resolve production problems (root-cause analysis)

• Ability to analyze and troubleshoot distributed database environments

• English proficiency B2/C1

Benefits

• Long-term project with an initial 3-month agreement and extension option

• Opportunity to take full technical responsibility for a key banking system and help build a local competence center

• Work in a multi-cloud environment (AWS + GCP) with a small international team

Nice to have

• Experience with Google BigQuery data warehouse

• Practical AWS and/or GCP cloud experience

• Experience in financial/banking/investment fund projects, especially ETFs

• Experience with additional Data/Python ecosystem tools and libraries