28.09.2026 aktualisiert

**** ******** ****
Premiumkunde
100 % verfügbar

Senior Java Fullstack Developer | Spring Boot, JEE

Pulheim, Deutschland
Weltweit
Diplom Informatiker (FH)
Pulheim, Deutschland
Weltweit
Diplom Informatiker (FH)

Profilanlagen

CV-Eugen-Reinus.pdf
CV-Eugen-Reinus-DE.pdf

Über mich

Seit 2005, nach meinem Informatik Studium (Diplom FH) habe ich in mehreren Branchen gearbeitet, schwerpunktmässig im Backend Bereich mit Java. Wobei ich immer wieder auch im Frontendbereich tätig war. Seit 03.2019 bin ich Freelancer.

Skills

JavaSpring SecurityJava SEJava BeansJava DevSpring FrameworkSoftware ArchitectureJava Application ServerSpring BootBackendBackend-programmierungFull Stack EntwicklungFront EndSpring Batch
Mein Schwerpunkt liegt auf der Entwicklung und Modernisierung von Java-basierten Backend- und Enterprise-Anwendungen sowie komplexen Softwaresystemen. Neben der eigentlichen Backend-Entwicklung gehören dabei regelmäßig auch Datenbankanbindungen, Frontend-Komponenten sowie Build-, Deployment- und DevOps-Aufgaben zum Projektumfang. Diese Bereiche betreue und entwickle ich bei Bedarf ebenfalls mit.

Im Folgenden sind die Frameworks, Technologien und Tools aufgeführt, mit denen ich schwerpunktmäßig gearbeitet habe:

Java Backend Development
Java, Jakarta EE, JEE, Spring, Spring Boot, Spring Batch, Spring Security, JPA, Hibernate, REST, OpenAPI, Swagger

Backend & Architecture
Backend Development, Enterprise Software Development, Microservices, Software Architecture, API Development, Legacy Modernization

Datenbanken & Search
SQL, Oracle Database, PL/SQL, PostgreSQL, Elasticsearch, Redis

Build, CI/CD & DevOps
Maven, Gradle, Git, Jenkins, Docker

Frontend & Fullstack
JavaScript, TypeScript, React, Vue.js, Angular.js, JSP, JSF, PrimeFaces, HTML, CSS

Weitere Technologien
Quarkus, Android Java und Kotlin, Java Swing

Testing
JUnit, Mockito, Selenium, JMeter

Erfahrung

Berufserfahrungmehr als 10 Jahre
Freelancer seit2019

Sprachen

DeutschverhandlungssicherEnglischgutRussischMuttersprache

Projekthistorie

Freelancer - Senior Software Engineer

Blinkenlights GmbH

Internet und Informationstechnologie

< 10 Mitarbeiter

Legacy System Modernization (Medical Sector)
Analyzed a 20-year-old, large-scale Java/Tomcat application (~2M
LOC) to propose a comprehensive modernization strategy using
AI-assisted tooling.
- AI Migration PoC: Developed a proof-of-concept leveraging AI
models to automate the migration of legacy JSP pages to modern
React components.
- Architecture Audit: Evaluated a custom Servlet-based backend
(no Spring/JEE) with ~0% test coverage; streamlined ongoing
migrations (Firebird to PostgreSQL) and redundant React state
management in a mixed JS/TS codebase.
- Production & Cluster Support: Resolved critical live-system issues
in a clustered environment, focusing on session handling,
Server-Sent Events (SSE), and license counting.
- Tech Stack: Java 11, Tomcat 9, Redis, PostgreSQL, Firebird, React
(JavaScript, TypeScript), Docker Compose, Claude, Codex, Gemini
CLI, IntelliJ.

Self-Directed Tech Sabbatical

Focused on upskilling and hands-on deep dives into
emerging technologies to expand my freelance service
portfolio. Developed several proof-of-concepts (PoCs)
and independent projects, including:
- CMDBlite: A lightweight, multi-tenant CMDB system with
integrated monitoring capabilities.
Tech Stack: Java, Quarkus (native build), SQLite, plain JavaScript,
htmx, Qute templating, Server-Sent Events (SSE), Docker.
- HN Client for Hacker News (Published Android App): A
minimalist Hacker News reader featuring a custom archive
function.
Tech Stack: Kotlin, Ktor-Client, Room (SQLite), Google Firebase,
on backend: Quarkus, REST, SQLite.
- AI Integration & Tooling: Evaluated capabilities and integration
patterns of the Gemini CLI AI tool.

Freelancer - Senior Software Engineer

Informationstechnikzentrum Bund (ITZBund)

Öffentlicher Dienst

1000-5000 Mitarbeiter

Software architecture, development
- Worked on a fiscal and security risk analysis of the customs
administration and the investigation services project
- Maintained and extended a JEE/Spring based risk management
system with a JSF/PrimeFaces frontend and Oracle database
- Except for the daily business as bugfixing and different
requirements implementations this are the most interesting
parts on which i worked on:
◦ worked on the new powerful search architecture with
Elasticsearch involved
◦ migrated some EJB-Services to Spring
◦ migrated RIKO-Application from JBoss-EAP 7.4 to 8.0
together with Spring Boot from 2.7 to 3.3
- Supported developer and test colleagues
- Prepared Jenkins jobs
- Main used technics: JavaEE (JSF/PrimeFaces, EJB, JPA/Hibernate),
Spring Boot, REST-Services, Elasticsearch, Oracle DB,
Maven, Jenkins, Git, IntelliJ IDEA,
Oracle WebLogic JEE Server, JBoss-EAP

Freelancer - Senior Software Engineer

GEBIT Solutions GmbH

Konsumgüter und Handel

50-250 Mitarbeiter

Software architecture, development

Project for a DIY store
  • Worked on an ERP system project
  • Implemented requirements and bugfixes on an existing ERP system
  • The ERP system based on a proprietary framework (TREND-Framework), which was used to extend and create GUIs, implement the business logic and test it

Project for a food-retailer/discounter
  • Worked on a checkout/till and related backoffice system
  • Implemented requirements and bugfixes on an existing codebase based on a proprietary framework (TREND-Framework) and tools
  • Main topics were: analyse requirements and bugs, extend and design till process workflows, extend and design reports, extend and design REST and SOAP interfaces for data import/export, code refactoring, define and write integration and unit tests, documentation, release preparation
  • Worked on a Python script for documentation export from proprietary documentation system (TREND/Analyst) to Atlassian-Confluence
  • Supported developer and test colleagues
  • Participated in code reviews
  • Main used technics: Java, proprietary framework (MDA, workflow, persistence, communication, GUI), Maven, Jenkins, PostgreSQL, H2 Database, Git, Eclipse with proprietary framework related plugins, proprietary framework for integration tests (Integrity), proprietary reporting engine, OpenAPI plugin for contract first interface definition, WildFly Application Server

Freelancer - Senior Software Engineer

USU Software AG / Project for Informationstechnikzentrum Bund (ITZBund)

Öffentlicher Dienst

1000-5000 Mitarbeiter

Software architecture, development
  • Worked on the DAC 6 project (DAC 6: EU tax disclosure rules)
  • Designed and implemented an Application based on Spring Batch Jobs to process tax arrangement data
  • Main topics were: technical sub-system design and documentation, generate large XML files (up to 100 MB) with JAXB, implement Oracle PL/SQL Procedures, Reporting SQL Views, different types of tests (Unit-Test; Integration-Tests; System-Tests; Stress-Tests)
  • Developed a WebApplication GUI with JSF/PrimeFaces with strict accessibility requirements especially for blind users
  • Define JUnit and Selenium Web-GUI tests
  • Prepare Jenkins jobs
  • Supported developer colleagues
  • Supported test team
  • Participated in code reviews
  • Main used technics: Spring, Spring Batch, Maven, Oracle, JSF/PrimeFaces, Eclipse

Freelancer - Senior Software Engineer

Plusnet GmbH

Telekommunikation

500-1000 Mitarbeiter

Software architecture, development
  • Implemented a GUI for a telecommunication carrier incident management system with PHP Symfony-Webframework and Vue.js
  • Supported the backend team on Spring Boot microservices development
  • Designed an external order interface architecture
  • Implemented a GUI for a product configuration system with PHP Symfony-Webframework and JavaScript
  • Main used technics: PHP Symfony-Webframework, Vue.js, Spring Boot, Maven, Oracle, IDEA IntelliJ

Senior Software Engineer

trimplement GmbH

Banken und Finanzdienstleistungen

10-50 Mitarbeiter

Software architecture, development
- Implemented CoreWallet payment gateway integrations for client-specific, local PSPs including corresponding payment method setup and routing
- Implemented a Processing and Routing Engine for Payments
- Implemented client-specific SPAs with Ember.js
- Implemented an SBE test framework and an exhaustive suite of SBE tests for a large client project
- Software engineer on the CoreWallet, balancr and CoreExchange products
- Implemented a highly customizable Sport Event Android App
- Integrated Google Maps and HERE Maps in Android
- Introduced GPS-Tracking and Video Playback
- Integrated Android Push-Notifications with Amazon Simple Notification Service (SNS)

Senior Java Developer

AXA Konzern AG

Versicherungen

>10.000 Mitarbeiter

Software architecture, development
- Cologne, Germany - Developed on a Deployment/Release Management System (Tomcat/JBoss, GWT)

Senior JEE Software Developer

QSC AG

Telekommunikation

1000-5000 Mitarbeiter

Software architecture, development
- Developed a Billing System which unified billing data from multiple legacy systems
- Developed a CRM System
- Developed several services and tools for Telecommunication typical scenarios (VPN-, Telephony-/Fax-, Telecommunication Port - Management Systems)

J2EE Software Developer

Atos Origin GmbH

Energie, Wasser und Umwelt

>10.000 Mitarbeiter

Software architecture, development
- Developed Java Applet, Struts and MS Excel VBA Applications for a natural gas exchange platform
- Developed a SOA sub system for message interchange with third-parties (TIBCO ESB, JMS, SOAP WebServices)

J2EE Software Developer

S4M - Solution for Media GmbH

Medien und Verlage

500-1000 Mitarbeiter

Software architecture, development
- Developed a highly customizable Billing System for TV-Commercials in context of AdManagement/Sales System
- Developed several Data Import/Export interfaces and tools
- Developed several Data Migration PL/SQL Scripts
- Developed several Report Data Collectors

.NET Software Developer

mz robolab GmbH

Industrie und Maschinenbau

< 10 Mitarbeiter

mz robolab GmbH Software development
Rheinbach, Germany Implemented a Industry Roboter Controlling Application on Windows Embedded CE device

.NET Software Developer

Ineas Versicherung GmbH

Versicherungen

250-500 Mitarbeiter

Software development
Implemented a Sync Web Tool to German Insurance Association (GDV)

Kontaktanfrage

Einloggen & anfragen.

Das Kontaktformular ist nur für eingeloggte Nutzer verfügbar.

RegistrierenAnmelden