(Senior) Data Engineer - Freelance

At Netguru, we're all about helping innovators and entrepreneurs shape the world through beautiful software. That is our mission.

With employees from 15+ different countries, we've worked with over 800 clients from more than 50 countries. To name some of them: OLX Motors Europe, UBS, Careem.

But we're not just another tech company. As a Certified B Corporation®, we're dedicated to creating an inclusive environment for all, and we take our commitment to sustainability seriously.

How freelancing works at Netguru?

We match you with work that fits your skills. Plus, you have access to various opportunities across different industries and companies. That means you will not only gain more experience but also develop various skills.

But there's more. Netguru freelancers can benefit from full-time collaboration and really be a part of the team.

So, are you ready to make an impact? Join Netguru, and let's build beautiful software together.

Role Overview

Senior Data Engineer responsible for working onsite with the client’s team in Warsaw. The role focuses on handling large and complex datasets, building and optimizing data pipelines, developing queries, and supporting annotation and evaluation tasks. Full-time engagement, five days per week at the office.

Details:

• Location: Warsaw (onsite, 5 days per week)
• Contract type: B2B
• Rate: up to €44/h (flexible, depending on experience)
• Start: ASAP
• Duration: ~6 months

Must-have:

• Proven experience as a Senior Data Engineer or in a similar data-focused role
• Expert-level SQL knowledge with the ability to write and optimize complex queries
• Proficiency in Python with focus on pandas and structured/unstructured data formats (JSON, CSV)
• Strong understanding of relational databases, schemas, indexing, and query optimization
• Experience with large datasets, data analysis, and handling edge cases
• Familiarity with annotation and evaluation tasks is an advantage
• Excellent documentation and communication skills
• High attention to detail and accuracy in data processing
• Knowledge of financial terminology, KPIs, and enterprise datasets is considered a plus

Responsibilities

• Develop, debug, and optimize advanced SQL queries across multiple dialects (PostgreSQL, MySQL, BigQuery, etc.)
• Work with large datasets, design and interpret database schemas, and identify data relationships.
• Perform data manipulation and analysis in Python (pandas, JSON, CSV)
• Generate natural language questions and corresponding SQL queries
• Evaluate model outputs, produce gold-standard annotations, and enriched responses.
• Prepare documentation and clear reasoning for downstream analysis
• Collaborate within the team, provide feedback, and contribute to process improvements
• Apply financial and business domain knowledge to ensure data quality and relevance

What's in it for you? Becoming a Netguru Freelancer means:

• Professionality: dev-friendly processes, like Continuous Integration and Code Review, work in line with Agile methodology.
• Diversity: projects from various industries like fintech, healthcare, insurance, or education.
• Growth: work with a team of experts and continuous development of your hard and soft skills.
• Curious to learn more about working as a Netguru freelancer? All the information you need is here: Netguru Talent Marketplace.

Looking for a full-time job? Check out our Career Page and find out more about our open recruitment processes.

Don't hesitate and apply right away!

At Netguru, we're committed to creating an inclusive environment for everyone. If you require any disability-related adaptations during the recruitment process, please let us know. We're here to help!