Lubos Krnac

lubos krnac

Senior/Lead Software Engineer, author, automation enthusiast and simplicity addict. I believe in continuous learning and power of TDD.

Stack Overflow profile

Author of

enterprise spring examples and integration tests

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Noticeable Stack Overflow badges:

  1. Golden badge in spring-boot tag. There are only 12 people on Earth owning this badge. I am one of few people owning this badge that doesn’t work on Spring Framework full time.
  2. Golden badge in spring tag. There are only 30+ people on Earth owning this badge.
  3. Golden badge in java tag. There are only 700+ people on Earth owning this badge.
  4. Bronze badges in various different tags: javascript, spring-test, junit, hibernate, dependency-injection, spring-mvc


Senior Software Engineer – (May 2023 - current)

Main Technologies:

  • UI: Typescript, Angular, RxJS, NgRx, StoryBlock, StoryBook
  • Backend: Java 21, Spring Boot, Spring MVC, Spring Security, Mapstruct, Maven, Spring Data JPA, MySQL, Spring Cloud AWS, Spring Cloud Gateway
  • Testing: Jest, Spock, Spring Test, Wiremock, TestContainers, JaCoCo
  • Infrastructure: AWS (ECS, RDS, MQ, Lambda, …), Ping Identity – PingOne
  • Monitoring: Dynatrace, Splunk
  • Static code analyzers: SonarQube

Selected Achievements:

  • Contributed to insurance claiming features of These are primary screens used by all customers in the product.
  • Main driver establishing monitoring culture: Enhancing Dynatrace Configuration, Analyzing/fixing various incidents. Mentored colleagues about Dynatrace features.
  • One of handful engineers contributed fullstack (backend as well as frontend part of codebase)
  • Mentoring teammates about various architecture/monitoring/infrastructure/testing/implementation topics

Lead Software Engineer – Dotsub (Jan 2016 → Apr 2023)

Main Technologies:

  • UI: Javascript, Typescript, ReactJS, Redux, Redux Toolkit, React Router, Create React App, PrimeReact,, video.js
  • Backend: Java, Spring Boot, Spring MVC, Spring Security, Mapstruct, Gradle, Spring Data JPA, PostreSQL, Activiti, Python, ffmpeg
  • Testing: React Testing Library, Jest, Mocha, Chai, Sinon, jUnit, Spring Test, Selenium, TestContainers, LocalStack, Mockito, Wiremock, JaCoCo,
  • Infrastructure: AWS (ECS, RDS, Lambda, MQ, Transcribe, Translate, …), Cloudflare, TravisCI, Terraform, Auth0, Azure Text to Speech, Various OVPs (Online Video Providers): BrightCove, YouTube, …
  • Monitoring: Datadog, Sentry, Freshping
  • Static code analyzers: SpotBugs, PMD, Checkstyle, ESLint, various custom Github PR checks

Selected Achievements:

  • Lead engineer shaping architecture, infrastructure, build/deployment automation, code quality and development standards of Video Translation Management System
  • Helped establish strong testing culture. 93+% test coverage including back-end and front-end code
  • Main contributor to key features, wide refactorings or performance enhancements
  • Introducing new patterns for production code and testing
  • Biggest contributor to very complex online Subtitle Editor screen based on React. Personally implemented various key features, performance enhancements and refactorings

Lead Software Engineer – Fidelity Investments (Nov 2014 - Jan 2016)

Main Technologies: Java 8, Spring Boot, Spring MVC, Spring Security, Spring Security OAuth2, Jenkins, Maven, TestNG, Spring Test, Mockito, TDD, Cucumber, BDD, Mybatis, JDBC, SQL, Oracle DB, REST, JSON Schema, Swagger, Spring Batch, Tomcat, Splunk, Nexus Repository, UDeploy, SonarQube, Fortify, PMD, FindBugs, CheckStyle, Cassandra, Apache Spark

Selected achievements:

  • Tech Lead / Senior SW Engineer working on Java based REST API Micro-services and Batch jobs
  • Drive automation initiatives across team ﴾Using Maven, Jenkins, Sonar, UDeploy﴿
  • Introducing, implementing, teaching modern development practices ﴾TDD, CI, CD﴿
  • Mentoring teammates of all experience levels
  • Go to person for design reviews and complicated problems solving across various teams
  • Working on relatively high load services ﴾serving 4 million requests/day; sometimes 80 requests/second during spikes﴿
  • Designing new and improving/enhancing existing common libraries used by various micro-services, e.g. for authentication,
  • Creator of project for exposing SQL commands and stored procedures as JSON web service with configuration only
  • Hands on Apache Spark and Apache Cassandra in POCs

Older Experience


Master’s degree in Software Engineering – University of Zilina, Slovakia
Specialization: Information and Control Systems




Java Code Geeks
Web Code Geeks

Older Experience

Senior Software Engineer – Sage (May 2013 - Nov 2014)

Main technologies: Java, Javascript, TDD, Spring, Spring MVC, Spring Security, Spring Integration, Spring Transactions, Spring JDBC, Tomcat, Hibernate, SQL, Oracle DB, SQL Server, TestNG, Mockito, PowerMock, Jenkins, JaCoCo, FindBugs, PMD, CheckStyle, SonarQube, React JS, Require JS, Angular JS, jQuery, CSS, HTML, Jasmine, Squire JS, Sinon

Selected achievements:

  • One of the developers shaping overall architecture of Sage CRM project
  • Security adviser for cloud and on‐premise installations
  • Corrected and mentored Test driven development process across all teams
  • Experience with modern JavaScript frameworks ﴾React, AngularJS, RequireJS﴿
  • Created client side unit testing suite for the first time on the project
  • Suggested and introduced various development process enhancements ﴾code review process suggestions, CI changes, TDD process improvements, Re‐factoring and Issue handling suggestions﴿
  • Mentoring junior and senior teammates

Java Software Engineer – Citco (May 2012 - Apr 2013)

Main technologies: Java, Spring, Spring JMS, ActiveMQ, WebSphere MQ, Hibernate, JPA, Oracle DB, Sybase DB, TestNG, Mockito, jMockit, Maven, Jenkins, jUnit, Spring‐JMX, FindBugs

Selected achievements:

  • Lead development role on crucial application within enterprise environment of market lead hedge fund administrator
  • Profiling, monitoring and tuning performance of application with high load data processing
  • Suggested and successfully integrated of most modern Java frameworks and methodologies ﴾e.g. automated testing, CI﴿ into the crucial Citco’s project
  • Mentoring junior teammates
  • Deploying applications into Solaris


  • NDCLoader ‐ Parses incoming messages ﴾trade requests, balances,…﴿, converts and stores them into normalized data container and routes data to various applications in Citco enterprise environment
    • Responsibilities: project tech lead; implementation of new multi‐threaded communication based on JMS; re‐design, optimization, refactoring and bug fixing of multi‐threaded processing and DAO layer; Export module
  • MQ library ‐ Library that simplifies JMS connections and resources handling. Can be used for Webpshere MQ and/or AcriveMQ ﴾full library design, implementation and maintenance﴿
  • TID service library ‐ Library that reads and pushes trade instrument identifiers from/to central data storage ﴾full library design, implementation and maintenance﴿

Software Engineer – Pilz (Nov 2011 - May 2012)

Main technologies: Java, Ant, jUnit, Hudson, Javascript, HTML, CSS, canvas, jQuery, C++, CMake, GNU Make

Selected achievements:

  • Fast discovery of software faults and bug fixing, refactoring of building scripts
  • Successfully used open‐source projects ﴾Webkit, Qt﴿ for building custom Web browser
  • Hands on Web development ﴾showcase and test applications﴿
  • Deploying applications into Windows and embedded Windows systems
  • Experience with CI, automated testing + discovered practical advantages of fast feedback loop


  • Visualization ‐ Solution for visualize and control automation process from PC and PMI5 device. Domain scripting language is used for automation logic and visualization
    • Tasks and responsibilities: fixing and refactoring project building scripts; domain scripting language compiler bug fixes and tests
  • Showcase web page ‐ Showcase web page for low resolution embedded device PMI5
  • Webkit based browser/QtWebkit based browser ‐ using C++ open source engine powering Chrome and Safari browsers

Java Software Engineer – Kios (Jan 2009 - Oct 2011)

Main technologies: Java, Gwt, Spring, Hibernate, Oracle DB, PostgreSql, jUnit, Ant, CSS, HTML, Javascript, JasperReports, Apache POI

Selected achievements:

  • Successfully deliver web applications using KTF ﴾KIOS technology framework﴿, Spring, Tomcat, Hibernate, GWT, Oracle/PostgreSQL
  • Effectively used Java based on principles of Design Patterns
  • Successfully and quickly learned lots of new technologies
  • Work on various enhancements and bug fixes of company internal framework ‐ KTF ﴾KIOS technology framework﴿
  • Participate on UML design using Enterprise Architect
  • Fast discovery of software faults and bug fixing
  • Deploying applications into Linux environment

Key Projects

  • DONet ‐ SW solution to process social welfare and pensions payments for Slovak Post Office
    • Worked on tasks and modules: multi‐threaded automatic tasks; report modules; imports from files; integration with external application ﴾XML﴿; optimization and bug fixing
  • KIOS technology framework ‐ Framework for mid‐size evidence systems of client‐server type
    • Worked on tasks and modules: GWT client side; client‐server servlet communication; notification module based on hibernate events; searching feature in Eclipse plug‐in for drawing UI interface; various enhancements and bug fixes
  • KINET ‐ Application for task management, CRM, document management and employee agenda
    • Worked on tasks and modules: GWT client; calendar and scheduling module; Projects, Tasks and Events modules; Email and SMS notification module

Embedded Software Developer – Siemens (Nov 2005 - Dec 2008)

Main technologies: C, C++, C#, .Net­2005, Assembly language, uCLinux, SMTP, Net-SNMP

Selected achievements:

  • Successfully cooperated on firmware development of leading device on the market (PowerLink)
  • Worked in international team (all projects were managed and developed in Vienna and I was outsourced to the Austrian branch of Siemens)
  • Designed and implemented desktop application for .NET platform
  • Effectively used C, C++ and C# language
  • Deploying applications into uCLinux embedded environment