10/17/2026 updated

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Java Tech Lead & Senior Software Engineer

warszawa, Poland
Germany +10
info: Germany, Austria, Italy, Hungary, Slovakia, Bulgaria, Poland, Romania, Czech Republic, Serbia, Bosnia-Herzegovina
Master of Science in Computer Science, Warsaw University of Technology
warszawa, Poland
Germany +10
info: Germany, Austria, Italy, Hungary, Slovakia, Bulgaria, Poland, Romania, Czech Republic, Serbia, Bosnia-Herzegovina
Master of Science in Computer Science, Warsaw University of Technology

Profile attachments

karol_świniarski_resume.pdf

Java (Programming Language)ScalaSpring BootRestful ApigRPC
Java & Spring Backend Development
Umfangreiche Erfahrung in der Entwicklung von Java- und Spring-basierten Microservices fuer verschiedene Branchen, darunter Gesundheitswesen, Energie, Fintech und Transport. Einsatz von Spring Boot, JavaFX, Vaadin und JSP fuer skalierbare Backend-Loesungen.

Software Architecture & Technical Leadership
Entwurf und Implementierung skalierbarer Systemarchitekturen auf Basis von Microservices, Domain-Driven Design (DDD), Hexagonal Architecture und dem C4 Model. Technische Fuehrung von Entwicklungsteams, Mentoring und Einfuehrung agiler Entwicklungsprozesse.

Cloud & Infrastructure (AWS, Docker, Kubernetes)
Deployment und Betrieb von Anwendungen auf AWS, GCP und Azure. Containerisierung mit Docker und Orchestrierung mit Kubernetes. Verwaltung von Cloud-Infrastrukturkosten sowie Monitoring mit Grafana.

Android & Mobile Development
Entwicklung nativer Android-Anwendungen mit Java und dem Android SDK, einschliesslich Android Automotive fuer Elektrofahrzeuge. Implementierung von UI-Komponenten, Backend-Integration und mobilen Kommunikationsprotokollen.

Messaging & Networking (Apache Kafka, gRPC, REST)
Implementierung von Kafka-basierter Inter-Service-Kommunikation sowie REST- und gRPC-Schnittstellen. Einsatz von OpenAPI fuer API-Spezifikationen und TCP/IP-Protokollen fuer Echtzeit-Datenuebertragung.

Testing & Quality Assurance
Entwicklung automatisierter und Integrationstests mit JUnit, Mockito, WireMock, Postman, Selenium und Espresso. Anwendung von TDD, Performance-Testing und Integrationstesting zur Sicherstellung der Softwarequalitaet.

CI/CD & Development Tools
Einsatz von Jenkins als primaeres CI/CD-Tool sowie Git, GitHub, GitLab, Gerrit und Mercurial fuer Versionskontrolle und Code-Reviews. Nutzung von IntelliJ IDEA, Jira und Git Flow im Entwicklungsalltag.

Databases
Erfahrung mit relationalen und nicht-relationalen Datenbanken, darunter MongoDB, PostgreSQL, MySQL und DynamoDB. Integration von Datenbankloesungen in Microservice-Architekturen.

C++ & Systems Programming
Entwicklung und Wartung von C++- und OpenGL-Code fuer mobile Betriebssysteme sowie Echtzeit-Simulatoren auf Basis des Ogre3D-Frameworks. Einsatz von C#/.NET Core in plattformubergreifenden Projekten.

Experience

Professional experience10+ years
Freelancer since2016

Languages

GermanBasic knowledgeEnglishFluentItalianBasic knowledgePolishNative speakerRussianBasic knowledge

Project history

Tech Lead

Trumin
Analyzed business requirements and designed scalable systems for OCR-based sports events using Java and Spring. Developed and maintained the platform, including MongoDB integration and JSP-based user interfaces. Designed and implemented integrations with mobile applications. Managed AWS infrastructure costs, balancing system performance, scalability, and operational expenses.

Java Tech Lead

Printoscope
Designed and implemented new architecture, delivered new features, and optimized existing code in distributed printing systems. Provided technical leadership, mentoring, and workshops for other developers. Improved the continuous delivery process and introduced an Agile/Scrum-based development workflow, along with team-building initiatives.

Senior Android Automotive Developer

Digiteq Automotive
Provided technical leadership and consulting for new and existing Android Automotive solutions for electric vehicles. Led and mentored team members, supporting their technical development and growth. Designed and developed internal tools to improve development workflow, automation, and team organization.

Senior Java Developer

Samsung
Developed new features for Java/Spring microservices supporting smartwatch health applications. Worked as part of a ten-person Scrum team. Implemented Kafka-based communication between services. Developed automated and integration tests using JUnit, Mockito, WireMock, and Postman. Used GitHub for daily development and Jenkins as the primary CI/CD tool, with applications deployed to AWS.

Java Developer

Infospread
Integrated two existing systems responsible for public transportation ticket sales and validation. Collaborated across two development teams and defined a common domain model using Domain-Driven Design (DDD). Designed a new API specification using OpenAPI and implemented an integration prototype based on Java/Spring microservices. Deployed the prototype to the GleSYS cloud environment. Developed and executed tests using JUnit and Postman.

Java Developer

ABB / Hitachi
Developed new features and maintained Java/Scala/Spring microservices for energy infrastructure failure prediction. Worked in a six-person Scrum team. Implemented Kafka-based inter-service communication. Developed automated and integration tests using JUnit, Mockito, WireMock, and Postman. Used GitHub for version control and Jenkins as the primary CI/CD tool. Deployed services to AWS and monitored the system using Grafana.

Founder & CEO

SnowBuddy
Founded and led SnowBuddy, a social networking platform for skiers and snowboarders across Europe. Conceived the product idea, designed the platform concept, and was responsible for the overall product and business direction. Led the development and launch of the platform, which went live in 2016. The project was discontinued in June 2021 following the significant impact of the COVID-19 pandemic on the winter tourism and ski industry.

Software Engineer

Sumo Logic
Worked on software for monitoring AWS infrastructure and identifying opportunities to reduce cloud infrastructure costs. Developed scripts and automation tools using Scala and Python. Contributed to solutions for monitoring infrastructure usage and optimizing AWS resource consumption and associated costs.

Software Architect

Fulmo
Designed and implemented a new platform for cryptocurrency/fiat wallets, exchange, and payment processing. Led a team of six developers and was responsible for architectural decisions and technical direction. Designed and implemented components using Java, Spring, JavaFX, C++, C#/.NET Core, and gRPC. Developed automated tests with JUnit and custom tools. Containerized and deployed the platform using Docker and Kubernetes on AWS.

Java Developer

X-Trade Brokers
Designed and implemented the user interface for a new binary options trading application. Developed and maintained Java backend services and delivered new features. Led a two-person development team. Developed Android components using Java and the native Android framework. Used JUnit for testing and Jenkins for continuous integration and automated builds. Applications were deployed on on-premises infrastructure.

Android Developer

X-Trade Brokers
Designed and implemented the user interface for a new online forex trading application. Led a four-person Scrum team responsible for mobile application development. Developed the application using Java and the native Android framework. Designed and implemented an efficient TCP/IP communication protocol for real-time, low-latency exchange of trading data. Developed automated tests using JUnit, Mockito, and Espresso. Used Jenkins for continuous integration and automated builds.

Android Developer

inFullMobile
Worked on a mobile application for a UK-based ticketing company, providing tickets for cinemas and other events. Developed and maintained features for the Android mobile application. Contributed to the implementation and integration of mobile functionality with backend services and ticketing systems.

Android Developer

Eniro
Worked on a mobile application providing telephone directory and local search services for the Polish and Swedish markets. Developed and maintained features for the Android mobile application. Contributed to the development and improvement of the application's user-facing functionality and integration with backend services.

C++ Developer

Samsung
Developed new features and maintained C++/OpenGL code for a web browser running on a new mobile operating system. Used Gerrit for version control, code reviews, and collaborative development.

Android Developer

Mobica
Designed and implemented a secure file storage application for Android. Led a two-person development team and was responsible for the technical implementation of the application.

Android Developer

Polidea
Designed and implemented various mobile applications using Java and the Android framework. Worked with both Mercurial and Git for version control and collaborative development. Used Jenkins for automated builds.

C++ Developer

Trinity-Interactive
Developed new features and maintained a real-time tank simulator using C++ and the Ogre3D graphics framework.

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