Andrzej Kostek - Senior Software Engineer

Q: Where is Andrzej based?

Andrzej is based in Warsaw, Poland .

Q: What languages does Andrzej speak?

Andrzej speaks the following languages: English (Advanced), Polish (Intermediate) .

Q: How many years of experience does Andrzej have?

Andrzej has at least 11 years of experience. During this time, Andrzej has worked in at least 3 different roles and for 3 different companies . The average length of individual experience is 4 years and 7 months . Note that Andrzej may not have shared all experience and actually has more experience.

Q: What is Andrzej's latest experience?

Andrzej's most recent position is Senior Software Engineer at UZ Leuven .

Q: What companies has Andrzej worked for in recent years?

In recent years, Andrzej has worked for UZ Leuven .

Q: Which industries is Andrzej most experienced in?

Andrzej is most experienced in industries like Information Technology and Healthcare .

Q: Which business areas is Andrzej most experienced in?

Andrzej is most experienced in business areas like Information Technology , Quality Assurance , and Business Intelligence .

Q: Which industries has Andrzej worked in recently?

Andrzej has recently worked in industries like Healthcare .

Q: Which business areas has Andrzej worked in recently?

Andrzej has recently worked in business areas like Information Technology and Quality Assurance .

Recommended expert

Warsaw, Poland

Experience

Jan 2021 - Present

5 years 3 months

Senior Software Engineer

UZ Leuven

Engineered RESTful APIs and Python-based services to integrate enterprise systems, enhancing data flow efficiency and response times by 30%.
Architected API modules for microservices using Java and Node.js, optimizing performance and scalability for high-volume requests in production.
Designed automated testing pipelines with Postman and Jest, improving API reliability and reducing bug incidence by 25% across deployments.
Collaborated with stakeholders to define API requirements, delivering solutions aligned with business logic and UKG Ready integration standards.
Optimized database queries and message queues, reducing latency by 20% for API endpoints and improving real-time data synchronization.
Guided junior engineers in API development best practices, testing methodologies, and integration patterns for high-quality system interfaces.
Integrated third-party applications and SaaS tools, ensuring seamless communication between UKG Ready systems and internal services.
Diagnosed performance bottlenecks in API modules, implementing caching and asynchronous techniques to enhance system throughput.
Coordinated cross-functional teams to align backend and front-end integrations, delivering consistent data structures and validated endpoints.
Engineered monitoring and logging solutions for API services, enabling faster incident response and improved operational reliability.
Delivered measurable improvement in system availability and API throughput, achieving 20% faster transaction processing across enterprise workflows.

May 2018 - Dec 2020

2 years 8 months

Software Engineer

Starschema

Developed API endpoints using Python and Node.js to support analytics dashboards, improving integration reliability by 15% for client systems.
Integrated multiple RESTful services with backend data stores, ensuring secure and efficient data access for complex business workflows.
Engineered reusable API modules to accelerate development cycles and reduce redundant coding across multiple projects and teams.
Collaborated with Agile teams to implement microservice patterns and CI/CD pipelines, improving deployment frequency and release predictability.
Implemented automated API testing frameworks with Postman and Jest, reducing error rates and improving code coverage by 18%.
Optimized API response times by evaluating query structures and implementing caching strategies, improving front-end performance.
Diagnosed integration challenges with third-party systems, proposing scalable solutions that aligned with client technical requirements.
Mentored junior developers on RESTful best practices, testing frameworks, and code review standards to enhance team productivity.
Delivered measurable outcomes in API reliability and maintainability, achieving higher client satisfaction and reduced incident tickets.

Jul 2015 - Apr 2018

2 years 10 months

Junior Software Engineer

Lingaro

Developed and maintained Python-based API endpoints for internal tools, improving data retrieval efficiency by 12% for analytics modules.
Assisted in integrating third-party REST APIs with backend systems, ensuring secure and accurate data exchange for reporting applications.
Collaborated with senior engineers to implement API testing procedures using Postman, increasing endpoint reliability and monitoring.
Contributed to unit testing and debugging, improving overall code quality and reducing integration issues for internal systems.
Supported team in code reviews and Agile ceremonies, learning best practices for API development and software deployment.
Optimized simple API workflows for data access and reporting, enhancing usability for business analysts and internal users.
Achieved measurable improvement in API responsiveness, gaining early recognition for efficient contributions to system integration tasks.

Industry Experience

See where this freelancer has spent most of their professional time.

Experienced in Information Technology and Healthcare.

Information Technology

Healthcare

Business Area Experience

See which departments and functions this freelancer has contributed to most.

Experienced in Information Technology, Quality Assurance, and Business Intelligence.

Information Technology

Quality Assurance

Business Intelligence

Summary

Senior software engineer with 10+ years of experience developing APIs, full-stack applications, and integrations using Python, Java, and Node.js. Expert in API design, RESTful services, and system integration, delivering optimized and scalable solutions for enterprise environments. Proficient in cloud platforms, CI/CD pipelines, and automated testing frameworks, ensuring robust and maintainable software delivery. Strong problem-solving and stakeholder collaboration skills, enabling seamless remote contributions to complex API-driven projects.

Skills

Programming & Frameworks:

Python
Java
Node.js
Restful Apis
Expressjs
Postman
Jest

Architecture & Design:

Microservices
Api-first Architecture
Tdd
Ci/cd
Modular Api Design

Cloud, Devops & Testing:

Aws
Azure
Docker
Kubernetes
Continuous Integration Pipelines
Automated Testing

Database & Messaging:

Postgresql
Mysql
Rabbitmq
Kafka
Swagger
Api Monitoring And Logging Tools

Soft Skills:

Remote Collaboration
Problem-solving
Stakeholder Communication
Agile Teamwork
Mentoring

Languages

English

Advanced

Polish

Intermediate

Education

Oct 2011 - Jun 2015

University of Warsaw

Bachelor of Arts, Computer Science · Computer Science · Warsaw, Poland

Statistics

Experience

Total positions 3

Experience in Information Technology 5.5 y

Avg length 3 y 6 m

Longest experience 5 y 2 m

Expertise

Recent roles Senior Software Engineer, Software Engineer, Junior Software Engineer

Main industries Information Technology, Healthcare

Main business areas Information Technology, Quality Assurance, Business Intelligence

Qualifications

Highest degree Bachelor

Profile

Created

October 2025

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Frequently asked questions

Do you have questions? Here you can find further information.

Where is Andrzej based?

Andrzej is based in Warsaw, Poland.

What languages does Andrzej speak?

Andrzej speaks the following languages: English (Advanced), Polish (Intermediate).

How many years of experience does Andrzej have?

Andrzej has at least 11 years of experience. During this time, Andrzej has worked in at least 3 different roles and for 3 different companies. The average length of individual experience is 4 years and 7 months. Note that Andrzej may not have shared all experience and actually has more experience.

What roles would Andrzej be best suited for?

Based on recent experience, Andrzej would be well-suited for roles such as: Senior Software Engineer, Software Engineer, Junior Software Engineer.

What is Andrzej's latest experience?

Andrzej's most recent position is Senior Software Engineer at UZ Leuven.

What companies has Andrzej worked for in recent years?

In recent years, Andrzej has worked for UZ Leuven.

Which industries is Andrzej most experienced in?

Andrzej is most experienced in industries like Information Technology and Healthcare.

Which business areas is Andrzej most experienced in?

Andrzej is most experienced in business areas like Information Technology, Quality Assurance, and Business Intelligence.

Which industries has Andrzej worked in recently?

Andrzej has recently worked in industries like Healthcare.

Which business areas has Andrzej worked in recently?

Andrzej has recently worked in business areas like Information Technology and Quality Assurance.

What is Andrzej's education?

Andrzej holds a Bachelor in Computer Science from University of Warsaw.

What is the availability of Andrzej?

The availability of Andrzej needs to be confirmed.

What is the rate of Andrzej?

Andrzej's rate depends on the specific project requirements. Please use the Meet button on the profile to schedule a meeting and discuss the details.