Habdas Waldemar Jacek

Led the design and development of Java-based microservices for high-traffic e-commerce platforms, improving system uptime by 25% through Spring Boot and Docker. Spearheaded the transition of legacy systems to cloud-native AWS architectures, optimizing resource usage and reducing cloud infrastructure costs by 15%. Implemented RESTful APIs using Spring Boot and AWS Lambda, supporting over 1 million active users globally. Architected the integration of containerized applications with Kubernetes, resulting in a faster deployment cycle and enhanced stability. Optimized database queries in PostgreSQL, reducing data retrieval times by 35%. Built a monitoring and alerting system with Prometheus and Grafana, cutting critical bug response times by 50%. Led a team of 5 engineers in Agile sprints, achieving on-time delivery. Enhanced frontend with React/Redux, improving user interaction. Introduced automated unit/integration testing with JUnit/Mockito, raising test coverage from 60% to 90%. Develo

Designed and implemented backend services in Java/Spring Boot processing over 500,000 transactions/day, ensuring scalability. Led integration of AWS services (S3, EC2, Lambda) to boost scalability and reduce costs by 20%. Migrated core functionalities from monolithic to microservices, improving scalability and reducing downtime during deployments by 60%. Collaborated with cross-functional teams to define product requirements and launch three major features in 2 months. Implemented OAuth2 authentication, reducing unauthorized access incidents by 40%. Containerized applications with Docker for consistent staging/production results. Wrote unit tests with JUnit/Mockito achieving ~95% code coverage; Kafka data pipelines handling over 1 million events/day; Frontend performance improvements with React/Redux; sprint planning with 95% completion; SQL query optimization; API documentation to aid developers.

Developed Java-based applications for the telecommunications industry with 100k+ daily active users. Designed and integrated RESTful services to improve data exchange speeds by 20%. Contributed to CRM system design with Spring MVC, improving access for sales team by 30%. Collaborated with QA to establish automated testing with JUnit/Selenium; performance tuning via multithreading and DB optimization reducing processing times by 35%. Wrote API/system design documentation, improved frontend with HTML5/CSS3/JS, implemented security enhancements, and integrated third-party payments increasing revenue by 15%. Mentored junior developers and refined client-server architecture reducing network latency by 40% for internal systems used by 500+ employees.