Patryk Niziołek

In early projects, I collaborated with small, agile teams and also led a project independently, where I delivered a fully functioning platform extension for an air carrier company. The goal was to implement secure REST API services for integrating with client applications. The project required a strong emphasis on security and API design best practices. I had the opportunity to gain experience working with large manufacturing facilities, for instance, in developing a layout for displaying KPIs on large screens in production lines. During these projects, I collaborated with international teams and effectively communicated in English. Following this, I gained experience in an R&D project for a watch company within a Scrum framework, actively participating in all Agile ceremonies (daily stand-ups, grooming sessions, sprint planning). This project, developed entirely in java, included dedicated QA and code review teams focused on specific modules, which allowed me to understand how to scale Feature Development and integrate efficiently into a large team. Currently, I am part of a Greenfield project, working from start to MVP. The platform is designed for system integration and workflow automation, with responsibilities including the design and implementation of Kafka-based messaging, REST, and SOAP services. I have been hands-on with technologies such as Spring, Kafka, Docker, React, and Angular to ensure a modern, scalable architecture. Throughout my journey, I have honed my ability to deliver both new feature requests and enhance existing systems with new functionalities.

Maintenance Project (Ticketing Systems — Two Major Polish Cities)
Full ownership of maintenance and development of two production backend systems for public transportation ticket sales. Designed and implemented integration modules for communication with a central system. Performed database optimization, including query tuning, indexing, and performance improvements. Refactored legacy code into a more modern, flexible, secure, and high-performance architecture. Ensured stability and reliability of business-critical systems. Acted as the final line of technical support in case of production incidents, system failures, and critical bugs. Implemented minor enhancements and fixes in the web-based administrative panel using Angular. Operated and developed containerized production applications deployed in the AWS cloud environment.

Greenfield Project (Modern Ticketing Platform)
Actively participated in building a new, scalable ticket sales platform from the ground up.

One of the main Java Backend Developers in a 3-person development team working in Scrum. The project is based on a microservices architecture using Spring Boot, Keycloak, Docker, AWS, and the LGTM observability stack.

Responsibilities and achievements: • Co-designed the backend microservices architecture together with a senior technical architect, focusing on scalability, reliability, and uninterrupted ticket sales. • Designed and implemented backend components for a ticketing application using Java and Spring Boot. • Designed the communication flow between the mobile application, BFF layer, and backend services, including token refresh mechanisms and Keycloak integration. • Worked extensively with Keycloak, OAuth2, and OIDC, including adding external OAuth providers, configuring authentication flows, and customizing UI and logic through Keycloak plugins. • Implemented additional authentication steps, including SMS code verification. • Built business logic responsible for refreshing operator-provided data, such as ticket price lists, while handling multi-city support, data validity periods, failure resilience, and continuous ticket sales requirements. • Integrated microservices using OpenFeign and communicated with external systems through REST Client. • Created dynamic API documentation using Swagger / OpenAPI, including support for cookie-based authentication provided by an OpenResty + Lua gateway layer. • Created and optimized Dockerfiles, including separating the application build stage using JDK from the runtime stage using JRE to reduce Docker image size. • Built a CI/CD pipeline in GitLab CI using GitLab Runners, with automated Docker image builds and publishing to Amazon ECR. • Worked with the application hosted on an AWS Linux server, including deployment, troubleshooting, and service diagnostics. • Helped introduce observability using the LGTM stack: Grafana, Prometheus, and Loki. • Took ownership of technical delivery when the senior developer / architect had limited availability. • Supported onboarding of a new developer by assigning tasks, reviewing code, and ensuring code quality before merging changes into the main branch. Technologies: Java, Spring Boot, Spring Cloud, Microservices, Keycloak, OAuth2, OIDC, REST, OpenFeign, Swagger / OpenAPI, Docker , GitLab CI/CD, GitLab Runners, AWS, Amazon ECR, Linux, Grafana, Prometheus, Loki, Scrum.