Patryk Czarnik – IT Expert

About Me

I am an experienced IT professional combining the roles of a software developer, systems analyst, and technical trainer. With over a decade of academic experience at the University of Warsaw and over 15 years in the commercial IT sector, I specialize in backend development, complex data processing, XML technologies, and database design.

Although my activities are miscellaneous, I identify myself primarily as a programmer. Working with code, as an author, teacher or reviewer, I pay a special attention to its quality and using best practices.

University background and different experiences gave me a solid basis in broad computer science, and in several areas I possessed expert knowledge and skills.

Core Competencies & Technologies

Java: Java SE/EE, Jakarta, Spring Boot, Web Services (SOAP/REST), JPA/Hibernate. (Oracle Certified Professional Java SE 8, Oracle Certified Expert Java EE 6)
Python: Core Python, Data Analysis (Pandas, Numpy, Matplotlib, Scikit-Learn).
XML Ecosystem: High expertise in XML Schema (XSD), XSLT, XQuery, XPath, and specialized document formats (e.g., financial and tax structures).
Databases (SQL): Advanced SQL querying, PL/SQL scripting, performance optimization, and database architecture. (Oracle Certified Expert, EnterpriseDB PostgreSQL Associate)
C & C++: Core C/C++, concurrent and network programming, UNIX/POSIX mechanisms.

Services & Consulting

Software Development

Backend-focused development and maintenance in Java, Python, C, or C++. Proficient in integrating APIs, resolving technical debt, and building robust backend architectures. Fluent Git usage and Bash scripting.

Data Processing & Migration

Data extraction, transformation, and analysis across varied formats (XML, JSON, CSV, SQL, EDIFACT). Applying Python (Pandas etc), SQL or XML tools (XSLT/XQuery) for data analysis and ML predictions.

XML Expert

End-to-end XML solutions, including complex XSD design and XSLT transformations.

Specialised Tools

Consulting on niche software such as Altova MapForce (data format transformations) and Adobe FrameMaker (Structured Applications / EDD).

IT Training & Workshops

Since 2008, I have delivered over 450 commercial training courses (totaling more than 2000 training days). I regularly collaborate with top Polish training centers (like ALX Academy) and offer dedicated B2B courses for corporate clients.

Available Topics: Java (Core, Spring, Web Services), Python (Core, Data Science), C/C++ (POSIX), XML Technologies, SQL (PostgreSQL, Oracle), and tools like Git and Bash.
Format: Available for remote or on-site sessions, tailored from beginner bootcamps to highly specialized advanced masterclasses.
Language: Basically, I conduct my trainings in Polish.

Find me on LinkedIn