Mario Jelinski
- +49 176 231 22 674
- [email protected]
- https://byte-union.com
- Goethepark 14 10627 Berlin
I am a software engineer since many years and worked for many projects with a proven ability to adapt in both self-starting and collaborative environments while staying focused on archieving high quality results under strict deadlines. I have experience in web design and development across diverse industries. Equipped with a record of success in consistently identifying und providing the technological needs of companies through ingenious innovation. Proficient in developing databases, creating user interfaces, writing and testing codes, troubeshooting simple / complex issues and implementing new features based on user feedback.
Work Experiences
Developer
Short-term project in the area of "handyhase," focusing on a comprehensive redesign.
Tasks and Focus Areas
- Redesign & Implementation: Overhaul of the entire design and implementation of new UI/UX aspects.
- Architecture & Structure: Planning of the software architecture and structuring of the project for long-term scalability.
Mobile Testing & Debugging
Implementation and optimization of mobile testing workflows using Firebase Test Lab for a Flutter and Dart-based mobile application.
Tasks and Focus Areas
- Test Automation: Developed and maintained automated test scripts for UI and functionality testing using Flutter's integration_test package.
- Firebase Test Lab Integration: Configured Firebase Test Lab to run tests on multiple devices and OS versions, ensuring broad compatibility.
- Error Detection & Reporting: Identified and documented bugs, performance issues, and crashes, providing detailed reports for the development team.
- CI/CD Pipeline: Integrated Firebase Test Lab into the CI/CD pipeline to enable automated testing with every build.
- Performance Optimization: Analyzed test results to identify performance bottlenecks and suggested improvements for the app's responsiveness and stability.
Developer
Led innovations in 3D printing and CNC machining, focusing on hardware customization, firmware development, and advanced material printing techniques.
Key Technologies
- Programming Languages: C, C++, QT QML
- Platforms: STM32 Microcontroller, GBRLHal
Key Contributions
- Firmware Development: Ported GBRLHal to a 32-bit STM32 microcontroller for enhanced 3D printing capabilities.
- CNC Machine Enhancement: Integrated cooling and color injection systems with customized firmware.
- Custom Print Head: Designed and implemented print heads for organic material printing.
- Layer Analysis: Developed image recognition systems for layer detection and monitoring.
- G-Code Conversion: Transformed MRI layers and artistic oil painting designs into G-code for precise 3D printing applications.
- GUI Development: Created a QT QML-based configuration and monitoring interface for image printing layers.
Developer
Key Technologies
- Programming Languages: Java 20 / Scala, PHP, Node.js, modern JavaScript (React).
- Frameworks & Tools: Java GWT 2.9, Hibernate, Spring Boot, Jenkins, Maven, Tomcat, Figma, OAuth 2.
- Data Management: AWS (up to 8 EBytes), GraphQL, SFTP (in PHP), Gitea (Git server), Cron Jobs.
- AI Development: GPT-4All for address validation, proprietary AI models (training & fine-tuning), AI tool for address detection.
- Frontend Development: Responsive interfaces with Vue, React and GWT
- Backend Development: Robust solutions using Java 20 and Node.js, including OAuth 2 implementations for secure authentication.
- Version Control: Git, GitTea, SVN
Project Highlights
- Digital Mail Services: Optimized processes such as printing, PDF conversion, text recognition, and digital signatures. (Fabric.JS)
- AI Tool for Address Detection: Developed a Vue-based training system for accurate address recognition.
- Automation: Managed cron jobs with PHP, Node.js, and Java.
- GraphQL Implementation: Optimized data queries and performed comprehensive log analyses.
- Secure Data Transfer: SFTP management in PHP for efficient and secure data exchange processes.
Additional Skills
- Management of ADFS servers and SAML 2.0.
- Setup of internal Git systems with Gitea and pipeline automation.
- Experience with large data handling and optimization of storage processes on AWS.
- Strong collaboration through pair programming to improve code quality and knowledge sharing.
Frontend Developer
Key Technologies
- Programming Languages & Frameworks: Vue, Stencil, React, JavaScript, Typescript, Flutter, Hotwire
- Tools & Platforms: AWS, Docker, Kubernetes, Azure, Firebase Labs.
- Version Control: Git, GitHub, GitHub Actions, Precommit Hooks, Testing Pipelines
Key Projects and Responsibilities
- Rebuilding Article Importer App: Redeveloped the existing Article Importer app using Vue and a REST API.
- Setting up New Projects: Established new projects with testing, linting, precommit hooks, and Git release pipelines.
- Improving Article Importer App: Updated the React-based Article Importer app with a REST API, fixed errors, and added new features.
- Developing a Soccer App: Created a new app for the 2022 World Cup featuring events, lineups, statistics, and knockout phase information, tested extensively using Firebase Labs to ensure compatibility across various mobile devices.
- Conducting Testing: Performed unit tests, integration tests, snapshot tests, and API mockup tests to achieve near 100% test coverage.
- Rebuilding with Vue: Migrated React-based projects to Vue and updated Vue2 projects to Vue3.
- Presenting Completed Work: Shared updates on completed work, including new features and improvements, in regular company-wide meetings.
Fullstack Developer
Modernizing a Market-Leading Funeral Software with 20 Years of Legacy
Key Technologies
- Technologies: React, JavaScript, Typescript, C#
- Component Development: Storybook, Figma
- API and State Management: REST APIs, Redux, React-hook-form
- Styling: Material-UI, CSS/Sass
Key Projects and Responsibilities
- Storybook-Based Development: Implemented Micro-Frontends using Storybook, and reused the same Storybook components in Vue, React, and Angular.
- API and State Management: Worked with REST APIs, Redux, and React-hook-form for efficient data handling.
- Styling: Designed and implemented styling solutions using Material-UI and CSS/Sass.
- Project Planning and Definition: Defined and planned new projects, including technology selection and timeline creation.
- Setting up New Projects: Established new projects with testing, linting, precommit hooks, and Git release pipelines.
- Releasing with Storybook Components: Designed a release process for utilizing Storybook components in multiple applications.
Software Developer / Lead
Led the modernization of enterprise systems by handling large data imports, building scalable applications, and migrating legacy platforms. Developed solutions for validating, merging, and exporting datasets, integrating custom scripting and no-code tools.
Key Technologies
- Programming Languages: Java (8+), Groovy, JavaScript (React, Node.js, Nuxt.js), Kotlin
- Frameworks & Tools: Spring Boot, Hibernate, Material-UI, Twig, Electron
- Data Management: PostgreSQL (hstore/jsonb), JDBC, node-postgres, XML, CSV, SAP
- CI/CD and DevOps: Jenkins, Apache Maven, ZooKeeper, Jetty, Tomcat, Ant
- Visualization: OpenMap, OpenLayers, Grafana
- Version Control: Git, SVN
Key Contributions
- Data Integration: Managed large data imports (SAP, Loga, CSV) into dynamic databases for validation and transformation.
- Platform Migration: Rebuilt a legacy Java-based platform (DHL) to JavaScript using React and Material-UI.
- Custom Scripting: Developed custom scripting and no-code tools for dataset validation and merging.
- Frontend & Backend Development: Created scalable web applications using React, Node.js, PHP, and Java Rich Client with WebSocket communication.
- Error Handling & Logging: Designed robust error-handling mechanisms and delta table logging with Grafana.
Senior Software Developer
Developed a cutting-edge 3D web application for particle-based fluid simulation, focusing on performance, scalability, and visualization.
Key Technologies
- Programming Languages: JavaScript (React, Node.js), Typescript, C++, Python
- Frameworks & Libraries: React, Three.js, Phaser, Redux, Nuxt.js
- Tools & Platforms: Docker, Kubernetes, Azure, Figma
- Version Control: Git, GitHub, GitHub Actions, Precommit Hooks, Testing Pipelines
Key Contributions
- 3D Web Development: Built interactive 3D visualizations for fluid simulations using React and Three.js.
- Simulation Integration: Worked on particle-based fluid simulations and extended Python functionality with C++ for performance optimization.
- Frontend Development: Created scalable, responsive web applications using React, Nuxt.js, and Redux.
- Cloud & DevOps: Deployed solutions using Docker, Kubernetes, and Azure for scalability and efficiency.
Senior Developer
Developed and enhanced solutions for email spam detection, implementing robust backend services and real-time monitoring systems.
Key Technologies
- Programming Languages: C++, Lua, Python, JavaScript, PHP
- Frameworks & Tools: Boost, React, Node.js, Django, Swagger, jQuery
- Data Management: MySQL, CouchDB
- DevOps & Monitoring: Docker, Kubernetes, Grafana
- Version Control: Git, GitHub, GitHub Actions, Precommit Hooks, Testing Pipelines
Key Contributions
- Email Spam Detection: Developed spam detection solutions using C++ and Lua, ensuring high accuracy and performance.
- Test-Driven Development: Followed TDD principles to build reliable unit tests in Python (pytest), Lua, and PHP, ensuring code quality and maintainability.
- Frontend Development: Enhanced the Pluto Customer Configuration Platform with React, Node.js, and jQuery, enabling seamless user interactions.
- Database Management: Optimized and managed MySQL and CouchDB for real-time data processing and storage.
- Real-Time Monitoring: Implemented real-time spam classification tracking with Grafana and custom monitoring tools.
- Agile Methodology: Collaborated in Scrum teams, participating in daily standups, sprint planning, and retrospectives to ensure efficient project delivery.
Software Developer
Contributed to the development and optimization of customer-facing platforms, including the Strato Customer Login, Server Login, and the IONOS product page.
Key Technologies
- Programming Languages: JavaScript (React, Vue, Angular, jQuery, Node.js), Typescript, PHP, Python, Java, Kotlin
- Frameworks & Tools: Phaser, Django, Symfony, Twig, Smarty, Bootstrap, Sass/Less, OAuth 2, Single Sign-On (SSO)
- Embedded Development: ESP32 low.js (embedded Node.js)
- Testing & Optimization: Selenium, JUnit, Unit Testing
- Cloud & Infrastructure: OpenStack, Servercloud
- Version Control: Git, GitHub, GitHub Actions, Precommit Hooks, Testing Pipelines
Key Contributions
- Platform Development: Built and maintained customer platforms, including rebranding for IONOS, using Django, JavaScript, and Python.
- Frontend Development: Designed responsive, interactive UIs with React, Vue, Angular, and Bootstrap for customer and server login portals.
- Authentication Systems: Implemented OAuth 2 and Single Sign-On (SSO) for seamless and secure user authentication across multiple platforms.
- Performance Optimization: Improved page speed from 7 seconds to under 950ms through advanced optimizations.
- Security Enhancements: Implemented robust protections against XSS (Cross-Site Scripting).
- UX Improvements: Conducted A/B tests and Multi-Armed Bandit tests for user experience optimization.
- Cloud Development: Worked on server cloud solutions using Java and OpenStack.
Software Developer
Contributed to feature testing, page optimization, and the development of backend and frontend solutions for Loquo and Alamaula.
Key Technologies
- Programming Languages: JavaScript, PHP, Java
- Frameworks & Tools: Prototype, jQuery, Smarty, CakePHP
- Data & Search: MySQL, MongoDB, Solr
- Infrastructure: OpenStack, Grafana
- Styling: CSS, SCSS
Key Contributions
- Fullstack Development: Developed and maintained backend and frontend features for Loquo and Alamaula platforms.
- SEO Optimization: Conducted search engine optimization and created sandbox environments for SEO testing across multiple websites.
- Error and Redirect Handling: Implemented error tracking and redirect management using Grafana, focusing on shingle creation and performance.
- Search Integration: Optimized search functionality using Solr for faster and more accurate results.
- Prototype and jQuery: Built responsive and dynamic interfaces with these libraries for frontend development (UX-Tests).
Software Developer
Developed and maintained a price comparison platform, focusing on CPC calculation, tracking, and monitoring sales to ensure legally compliant invoicing.
Key Technologies
- Programming Languages: PHP, C, JavaScript (jQuery), R (for statistical analysis)
- Databases: PostgreSQL, CouchDB
- Search & Data: Solr, vector-based data mapping
Key Contributions
- Platform Development: Built and enhanced the price comparison platform, focusing on scalability and performance.
- CPC Calculation: Developed and monitored systems for click-based cost calculations and legally secured invoicing.
- Search Engine Optimization: Optimized the platform for search engines, improving visibility and traffic.
- Data Mapping: Implemented vector-based data mapping for efficient offer matching.
- Custom Framework: Designed and implemented a custom MVC-based framework for the platform.
- Monitoring & Tracking: Analyzed traffic and tracked outgoing clicks to calculate customer invoices accurately.
Software Developer
Contributed to the development of advanced image processing tools and calibration systems for ePass Readers used by the Bundesdruckerei.
Key Technologies
- Programming Languages: C, C++, PHP
- Libraries & Tools: Halcon, Boost, Qt
- Standards: SOAP, WSDL
- Methodologies: Requirements analysis, UML
Key Contributions
- Embedded Programming: Developed image recognition and processing software for the new ePass Readers.
- Calibration Tool: Created a calibration tool for ePass Readers using Halcon, C/C++, Boost, and Qt.
- Specification & Analysis: Collaborated on specification documents and performed requirements analysis using UML.
- Web-Based Solutions: Developed a PHP-based project management tool to support internal workflows.
Game Developer
Developed the video game adaptation of the movie Die wilden Kerle 5 and a trading card game for the Wii, focusing on game logic, tools, and platform-specific programming.
Key Technologies
- Programming Languages: Assembler, C, C++, C#
- Game Development Tools: Custom script language, level editors
- Platforms: Nintendo DS, Wii
Key Contributions
- Platform-Specific Development: Created Nintendo DS game mechanics using Assembler, C, and C++.
- Game Logic: Designed and implemented game logic using a custom scripting language.
- Tool Development: Built level editors in C# to streamline game design processes.
Developer
Worked on cable modem design and conducted stress tests for cable network infrastructure.
Key Technologies
- Programming Languages: Java, Perl
Key Contributions
- Cable Modem Design: Contributed to the design and development of cable modems.
- Network Stress Testing: Conducted performance and stress tests on cable networks using Java and Perl.
Working student - IT-Helpdesk
Provided IT support and administration for the Siemens network, ensuring smooth operations and effective hardware and software configurations.
Key Contributions
- Network Administration: Managed and maintained Siemens network infrastructure.
- Hardware & Software Configuration: Configured and deployed new hardware and software for internal use.
- Gas Turbine Monitoring: Conducted monitoring and measurement activities for gas turbines.
Developer / Administration
- ERA employee management software
Student
- Smartcard login system for hospitals