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Hi There, I'm Tomas senior Java/Scala & web developer in Prague, Czech republic. My mother tongue is Czech and I can fluently speak English. My experiences range from building simple responsive web sites to designing large scalable systems for financial business. I like working in a team that cares about design quality and solution's maintainability. I excel in solution design, Java based technologies and I'm fast in learning new technologies. I'm flexible in my working hours and happy yo work with other freelancers you wor with. I'm looking forward to solve your IT problems for you!

Senior Java Developer with 7+ years building production microservices and integration platforms for banking and financial systems. Based in Prague, Czech Republic, with an MSc in Informatics (Czech University of Life Sciences, 2025). I specialise in: • Backend Java (17/21) with Spring Boot 3.x, Spring Security, and Spring Cloud • Event-driven architecture using Apache Kafka and RabbitMQ • API design (REST/OpenAPI 3.x), Kong API Gateway, and MuleSoft integrations • Identity and security: Keycloak, OAuth 2.0/OIDC, HashiCorp Vault • Databases: PostgreSQL, Oracle, MongoDB — including live migration projects • DevOps: Docker, Kubernetes, Helm, GitLab CI/CD, GitHub Actions • Observability: OpenTelemetry, Prometheus, Grafana, Loki, Splunk • Testing: Testcontainers, JUnit 5, WireMock, Allure Report I deliver clean, well-tested, production-ready code and take full ownership from requirements through deployment. I work well in distributed teams across European time zones and communicate clearly in English. Available for backend Java projects, API development, system integration, and architecture consulting.

I worked on Upwork during it was still Odesk ( May 2011 - Aug 2013 ). After this, up until September 2018, I concentrated on JavaScript and Python. I developed front-end web applications using AngularJS, Bootstrap, HTML5, CSS3, ReactJS, jQuery, Webpack. As for back-end I worked with Django REST Framework. Also, I was developing back-end with PHP and Laravel framework. Now I am starting on Upwork again combining with my full time job.

I’m a technical QA engineer who finds issues before users do—across UI, APIs, and data. I write clear bug reports, validate complex flows, and build automation that reduces regression risk and speeds up releases. With ~10 years in Java and QA automation lead experience in product companies (iGaming), I’ve built custom, maintainable test frameworks and stabilized CI pipelines. I can help with: * Manual QA: functional/regression/exploratory testing, UX issues, release checklists * API & technical validation: Postman/RestAssured, JSON validation, logs/data checks * Automation: Selenium UI + API tests (JUnit/RestAssured, custom frameworks), Testcontainers, Allure, CI integration * Performance: JMeter/Gatling (optional) I’m happy to start manually and add automation where it gives the highest ROI. Open to a short paid trial (5–10 hours) to prove fit quickly.

Thanks for looking at my profile. Please DON'T consider hiring me if: - you are looking for beginner/mediocre developer who will do the job for you as cheap as possible - think you are the smartest person in the universe (neither am I) - don't want to discuss/answer questions, share a wider context about your project. I want to provide my services as I if was your business partner - my work doesn't create more value for you than your investment in my work ------------------------------------------------------------- Here are feedbacks from my previous clients: "Everything was done perfectly." "Zdenko has strong Python coding expertise and good architectural knowledge of the Google Cloud Platform. He provided valuable architectural and project guidance. Zdenko was responsive provided excellent documentation with his insights that were valuable." Zdenko was a great developer to work with. He is very knowledgeable of Google Could Platform and understood the task which needed to be done without excessive guidance. I would highly recommend Zdenko to anyone looking to develop a data pipeline in the cloud. "Fantastic person and hard working! He delivered quality work and knew exactly what was needed to complete the job." Working with Zdenko was incredibly easy, and he produced exactly the results we were looking for. Communication was excellent via messaging on UpWork. I would highly recommend Zdenko. "Great Job! He knows GAE very well and was able to do everything we asked for. great python developer. yet again we are going to hire him immediately" "He let me know exactly what I needed to give him, and he didn't waste any time in getting it done. He also knew to do a couple of things that I didn't explicitly ask him to do when we started, but which clearly needed to be accomplished as part of the larger task." ------------------------- During my years as a software consultant, I have realized that communication with the client is most crucial. That's why I make every effort to understand the requirements of the task that's needed to be done, remove ambiguities, make a thorough analysis, suggest a solution, and implement. For several years now I'm focused on deploying web apps and big data pipelines on Google Cloud Platform and using its products (Google App Engine, Cloud Run, Cloud Functions, Google Compute Engine, BigQuery, Dataflow, etc). I write about it on my personal page and answer questions on Quora My expertise is in programming Python web/data applications. I use mostly Django, Flask, Webapp2 frameworks. Besides that, I have knowledge of other web technologies (HTML, CSS, Javascript...). I am very open to new challenges and problems. I prefer working on Linux. I am constantly improving my skills and knowledge in all areas. Experience with scrapping e-shops, real estate websites using BeautifulSoup I'm not a frontend guru, if necessary I can work with Bootstrap and a little bit of Javascript

I am a DevOps and Event Streaming Engineer with strong expertise in cloud infrastructure, CI/CD automation (Jenkins, Gitlab CI), containerization (Docker, Kubernetes), and real-time data streaming (Kafka, Pulsar). Beyond development (Java, Python, JavaScript), I specialize in designing scalable architectures and solutions on Kafka, ensuring efficient data flow, fault tolerance, and high availability for event-driven applications.