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Matija Krajnik
Zagreb, Croatia
FER Zagreb grad and Elixir enthusiast with a QA automation background who's fallen for the Phoenix framework's charms. I build fault-tolerant systems while maintaining my QA sixth sense for hunting edge cases. My testing expertise spans Web/Mobile GUIs and APIs, with solid Ruby experience from my automation days. When not pattern-matching my way through problems that would break a switch statement, I'm dabbling in Golang - because apparently, one programming language just isn't enough.
CodersRank Score
What is this?
This represents your current experience. It calculates by analyzing your connected repositories. By measuring your skills by your code, we are creating the ranking, so you can know how good are you comparing to another developers and what you have to improve to be better
Information on how to increase score and ranking details you can find in this blog post.
142.6
CodersRank Rank
Top 5%
Top 5
Elixir
Developer
Croatia
Top 5
Go
Developer
Croatia
Top 10
Ruby
Developer
Croatia
Highest experience points: 0 points,
0 activities in the last year
Go
58.9
exp.
Elixir
41.7
exp.
JavaScript
33.4
exp.
JSON
2.7
exp.
Ruby
1.9
exp.
Shell
1.7
exp.
List your work history, including any contracts or internships
Tentamen d.o.o
11 years 3 months
Full Stack Elixir/Phoenix Developer
May 2024 - May 2025 (1 year)
# Technologies:
1. Backend: Elixir, Phoenix Framework, OTP, Oban
2. Frontend: Phoenix LiveView, JavaScript, TailwindCSS
3. Database: PostgreSQL, Ecto, Scrivener (pagination)
4. AI/Integration: OpenAI API, Geocoding API, JSON processing (Jason)
5. DevOps: Docker, Fly.io, GitHub Actions CI/CD pipeline
6. Testing: ExUnit, ExCoveralls, Ex Machina, Efx
7. Quality: Credo, Formatter
# Responsibilities:
1. Design, develop, and maintain web application processing 500+ daily news reports using Elixir and Phoenix framework
2. Build interactive, real-time user interfaces with Phoenix LiveView achieving <200ms update latency
3. Implement responsive front-end components using LiveView, HTML5, and CSS with 100% mobile compatibility
4. Design and implement database schemas and queries handling 30,000+ records with Ecto
5. Implement background job processing with Oban managing multiple daily tasks with 99.9% reliability
7. Write comprehensive tests using ExUnit, Ex Machina and Efx maintaining 93%+ code coverage
8. Ensure code quality through Credo checks with zero critical issues in production code
9. Integrate with AI (LLM) models API to process 500+ news reports daily
10. Support geocoding and location-based features
11. Troubleshoot and debug system issues reducing error rates
12. Contribute to technical documentation covering core application features
# Achievements:
1. Reduce application response time by 40% through query optimization and caching implementation
2. Improve geocoding accuracy from through real-time data analysis and improved processing of known special cases
3. Refactored core processing logic by implementing modular architecture, improving testability through dependency injection, enhancing readability with consistent patterns, and adding logging for faster troubleshooting.
4. Reduced test suite execution time by 30% through implementation of asynchronous testing patterns while maintaining comprehensive test coverage
1. Backend: Elixir, Phoenix Framework, OTP, Oban
2. Frontend: Phoenix LiveView, JavaScript, TailwindCSS
3. Database: PostgreSQL, Ecto, Scrivener (pagination)
4. AI/Integration: OpenAI API, Geocoding API, JSON processing (Jason)
5. DevOps: Docker, Fly.io, GitHub Actions CI/CD pipeline
6. Testing: ExUnit, ExCoveralls, Ex Machina, Efx
7. Quality: Credo, Formatter
# Responsibilities:
1. Design, develop, and maintain web application processing 500+ daily news reports using Elixir and Phoenix framework
2. Build interactive, real-time user interfaces with Phoenix LiveView achieving <200ms update latency
3. Implement responsive front-end components using LiveView, HTML5, and CSS with 100% mobile compatibility
4. Design and implement database schemas and queries handling 30,000+ records with Ecto
5. Implement background job processing with Oban managing multiple daily tasks with 99.9% reliability
7. Write comprehensive tests using ExUnit, Ex Machina and Efx maintaining 93%+ code coverage
8. Ensure code quality through Credo checks with zero critical issues in production code
9. Integrate with AI (LLM) models API to process 500+ news reports daily
10. Support geocoding and location-based features
11. Troubleshoot and debug system issues reducing error rates
12. Contribute to technical documentation covering core application features
# Achievements:
1. Reduce application response time by 40% through query optimization and caching implementation
2. Improve geocoding accuracy from through real-time data analysis and improved processing of known special cases
3. Refactored core processing logic by implementing modular architecture, improving testability through dependency injection, enhancing readability with consistent patterns, and adding logging for faster troubleshooting.
4. Reduced test suite execution time by 30% through implementation of asynchronous testing patterns while maintaining comprehensive test coverage
QA Automation Engineer
Feb 2014 - May 2024 (10 years 3 months)
# Technologies:
1. Automation: Selenium WebDriver, custom testing frameworks, scripting languages
2. Web & Mobile: Cross-browser testing, Android application testing
3. Infrastructure: Hardware integration testing, connectivity validation
4. CI/CD: Test pipeline integration, automated reporting
5. Management: Issue tracking systems, test documentation tools
# Responsibilities:
1. Design and implement automated tests for complex web and mobile applications
2. Develop custom testing tools and frameworks enhancing team efficiency
3. Execute manual testing for specialized hardware integration scenarios
4. Create comprehensive test documentation and release reports
5. Lead automation initiatives and mentor team members on best practices
6. Collaborate with development teams to understand requirements and prioritize testing
7. Configure and maintain CI/CD pipelines for continuous test execution
8. Validate specialized domain functionality (healthcare data, network connectivity)
9. Perform cross-browser and platform compatibility testing
10. Troubleshoot testing infrastructure and resolve technical challenges
# Achievements:
1. Transformed predominantly manual processes through strategic test automation
2. Developed custom tools and libraries decreasing test development time
3. Created robust frameworks supporting multiple platforms and applications
4. Improved test execution efficiency through CI/CD integration
5. Implemented comprehensive testing identifying critical issues before release
6. Established standardized reporting improving communication between teams
7. Designed modular test architecture enabling code reuse across projects
8. Reduced regression testing time while increasing test coverage
1. Automation: Selenium WebDriver, custom testing frameworks, scripting languages
2. Web & Mobile: Cross-browser testing, Android application testing
3. Infrastructure: Hardware integration testing, connectivity validation
4. CI/CD: Test pipeline integration, automated reporting
5. Management: Issue tracking systems, test documentation tools
# Responsibilities:
1. Design and implement automated tests for complex web and mobile applications
2. Develop custom testing tools and frameworks enhancing team efficiency
3. Execute manual testing for specialized hardware integration scenarios
4. Create comprehensive test documentation and release reports
5. Lead automation initiatives and mentor team members on best practices
6. Collaborate with development teams to understand requirements and prioritize testing
7. Configure and maintain CI/CD pipelines for continuous test execution
8. Validate specialized domain functionality (healthcare data, network connectivity)
9. Perform cross-browser and platform compatibility testing
10. Troubleshoot testing infrastructure and resolve technical challenges
# Achievements:
1. Transformed predominantly manual processes through strategic test automation
2. Developed custom tools and libraries decreasing test development time
3. Created robust frameworks supporting multiple platforms and applications
4. Improved test execution efficiency through CI/CD integration
5. Implemented comprehensive testing identifying critical issues before release
6. Established standardized reporting improving communication between teams
7. Designed modular test architecture enabling code reuse across projects
8. Reduced regression testing time while increasing test coverage
Ericsson Nikola Tesla
May 2015 - May 2024 (9 years)
QA Automation Engineer
# Technologies:
1. Automation: Ruby, Watir/Selenium WebDriver, Cucumber BDD framework
2. Development: Custom CLI tools, Ruby libraries
3. Web Testing: Watir, browser automation for multiple browsers
4. Mobile Testing: Android automation frameworks, physical device testing
5. Infrastructure: MiniPC hardware, 3G/4G connectivity testing tools
6. CI/CD: GitLab pipelines, test automation integration
7. Management: Jira, Excel reporting templates, test documentation
8. Communication: Collaboration tools for cross-functional team integration
# Responsibilities:
1. Lead automation strategy and implementation for QA team of 2-3 engineers
2. Mentor QA team members on automation best practices, Ruby, and test development
3. Design and implement end-to-end automated tests for web applications processing 400+ test cases
4. Develop automated test suites for Android mobile applications covering 90%+ of functionality
5. Create and maintain custom libraries and CLI tools reducing manual testing effort
6. Configure and execute GitLab CI/CD pipeline running automated tests daily
7. Conduct manual testing for hardware-specific scenarios
8. Generate comprehensive test reports for each release cycle
9. Produce performance test reports analyzing system behavior under various conditions
10. Collaborate with team of 10-12 developers to understand requirements and prioritize testing
11. Troubleshoot and debug testing infrastructure issues with minimal downtime
# Achievements:
1. Developed custom Ruby libraries decreasing test script development time by 50%
2. Implemented automated end-to-end tests identifying 95% of critical issues before release
3. Reduced regression testing time from 24 to 4 hours through rewriting old tests
4. Designed modular test architecture enabling code reuse across multiple test suites
1. Automation: Ruby, Watir/Selenium WebDriver, Cucumber BDD framework
2. Development: Custom CLI tools, Ruby libraries
3. Web Testing: Watir, browser automation for multiple browsers
4. Mobile Testing: Android automation frameworks, physical device testing
5. Infrastructure: MiniPC hardware, 3G/4G connectivity testing tools
6. CI/CD: GitLab pipelines, test automation integration
7. Management: Jira, Excel reporting templates, test documentation
8. Communication: Collaboration tools for cross-functional team integration
# Responsibilities:
1. Lead automation strategy and implementation for QA team of 2-3 engineers
2. Mentor QA team members on automation best practices, Ruby, and test development
3. Design and implement end-to-end automated tests for web applications processing 400+ test cases
4. Develop automated test suites for Android mobile applications covering 90%+ of functionality
5. Create and maintain custom libraries and CLI tools reducing manual testing effort
6. Configure and execute GitLab CI/CD pipeline running automated tests daily
7. Conduct manual testing for hardware-specific scenarios
8. Generate comprehensive test reports for each release cycle
9. Produce performance test reports analyzing system behavior under various conditions
10. Collaborate with team of 10-12 developers to understand requirements and prioritize testing
11. Troubleshoot and debug testing infrastructure issues with minimal downtime
# Achievements:
1. Developed custom Ruby libraries decreasing test script development time by 50%
2. Implemented automated end-to-end tests identifying 95% of critical issues before release
3. Reduced regression testing time from 24 to 4 hours through rewriting old tests
4. Designed modular test architecture enabling code reuse across multiple test suites
SnapMD
Oct 2014 - Apr 2015 (6 months)
QA Automation Engineer
# Technologies:
1. Automation: Selenium WebDriver, C#
2. Web Testing: Cross-browser compatibility testing (Chrome, Firefox, Safari, IE/Edge)
# Responsibilities:
1. Execute comprehensive manual test cases for Virtual Care Management (VCM) Telehealth Platform
2. Develop and maintain automated test suites covering 70%+ of critical functionality
3. Test secure messaging features
4. Participate in Agile ceremonies providing QA perspective for 2-week sprint cycles
# Achievements:
1. Increased test automation coverage reducing manual testing effort
2. Identified most critical issues before production deployment
3. Identified multiple security vulnerabilities (XSS and CSRF) and improved team security awareness
1. Automation: Selenium WebDriver, C#
2. Web Testing: Cross-browser compatibility testing (Chrome, Firefox, Safari, IE/Edge)
# Responsibilities:
1. Execute comprehensive manual test cases for Virtual Care Management (VCM) Telehealth Platform
2. Develop and maintain automated test suites covering 70%+ of critical functionality
3. Test secure messaging features
4. Participate in Agile ceremonies providing QA perspective for 2-week sprint cycles
# Achievements:
1. Increased test automation coverage reducing manual testing effort
2. Identified most critical issues before production deployment
3. Identified multiple security vulnerabilities (XSS and CSRF) and improved team security awareness
Add some compelling projects here to demonstrate your experience
RGB (React Gin Blog)
May 2021 - Jun 2021
Let's Code
Guide explaining how to build full stack Web App from scratch using Go programming language with Gin and React frameworks.
CrimeBeats
Jul 2024 - Present
Tentamen d.o.o
CrimeBeats is an interactive web application that transforms daily police reports from Zagreb into visual insights. Users can explore crime incidents displayed as pins on an interactive map, with detailed information extracted through AI technology. The platform allows filtering incidents by date range and crime type, or searching for specific locations to monitor neighborhood safety. Beyond the map view, CrimeBeats offers comprehensive crime statistics with trends and analysis to help users understand safety patterns across different city districts. Users can also subscribe to location-based alerts to stay informed about incidents in areas of interest.
This section lets you add any degrees or diplomas you have earned.
Faculty of Electrical Engineering and Computing, University of Zagreb
Bachelor of Science in Computing
Oct 2008 - Jul 2012
Faculty of Electrical Engineering and Computing, University of Zagreb
Master of Science in Information and communication technology
Oct 2012 - Jul 2014
Association for Software Testing
Black Box Software Testing Foundations Course
May 2015