26.07.2026 aktualisiert
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Senior Java Backend Developer & System Architect
Escheburg, Deutschland
Nur Remote
MSc in Applied MathematicsÜber mich
Freelance Senior Java Developer and System Architect with 20+ years of experience designing, building, and modernizing backend systems. Experienced with both greenfield development and refactoring complex legacy architectures for performance, scalability, and maintainability.
Skills
HTMLJavaAPIsCloud ComputingApache LuceneDatenbankenContinuous IntegrationDistributed ComputingHibernateJava Database ConnectivityJava Message ServiceJava Persistence APIServletPostgreSQLApache Maven
Java Enterprise Development
Java 6/8/11/21 development with Spring Boot, Spring Data, MVC, IoC, JPA/Hibernate, JDBC, and JMS frameworks for enterprise applications
System Architecture & Microservices
Microservices architecture design with REST and SOAP APIs, SSO implementation, distributed systems, and clustering solutions
Database Management
PostgreSQL, Oracle, MSSQL, MySQL, Redis, and Elastic/Lucene database technologies for data storage and retrieval
DevOps & CI/CD
Git/SVN version control, Maven, Nexus, GitLab CI/CD, Docker containerization, Portainer, Kubernetes orchestration, and Spring Cloud deployment
Frontend Technologies
React development and vanilla HTML/JS for user interface implementation
Cloud Platforms
Google Cloud Platform experience with containerized deployments and cloud-native solutions
Operating Systems & Networking
Linux/Unix systems administration with over 10 years of experience, TCP/IP protocols, Cisco routing, and ISP network maintenance
Legacy System Integration
JSF/JSP/Servlets, JBoss AS/Seam integration, and modernization of legacy applications
Erfahrung
Berufserfahrungmehr als 10 Jahre
Freelancer seit2017
Sprachen
DeutschverhandlungssicherEnglischverhandlungssicherRussischMuttersprache
Projekthistorie
- Hands-on development and integration of multiple backend services for fleet management systems.
- Development of an AI‑driven chatbot as part of the company’s customer support platform
- Worked on legacy migrations (Java 6/8/11/21, SpringBoot2/3), partner system integrations (SOAP, REST).
- Implemented SSO (Keycloak OAuth2) and participated in architecture reviews and CI/CD setup.
- Tech: Java 11-21, Spring, Oracle, PostgreSQL, JDBC/JDBI, SOAP/REST, React
- Hands-on Entwicklung und Integration mehrerer Backend-Services für Flottenmanagementsysteme
- Entwicklung eines KI-basierten Chatbots als Bestandteil der Customer-Support-Plattform
- Migration und Modernisierung von Legacy-Systemen (Java 6/8/11/21, Spring Boot 2/3)
- Integration externer Partner-Systeme (SOAP, REST)
- Implementierung von SSO (Keycloak OAuth2) sowie Mitarbeit bei Architektur-Reviews und CI/CD-Setups
- Technologien: Java 11-21, Spring, Oracle, PostgreSQL, JDBC/JDBI, SOAP/REST, React
- Hands-on development of core backend components and critical system features.
- Led engineering and system architecture for a proptech startup, delivering MVP and subsequent releases.
- Migrated backend from Kotlin to Java (Spring Boot), improving maintainability and developer velocity.
- Designed and developed a full-cycle platform for rentable real estate construction (Java + React).
- Built team processes, CI/CD pipelines, and containerized deployments on Google Cloud.
- Earned company equity for contributions to the product foundation.
- Tech: Java 11-21, Spring, Thymeleaf, Google Cloud, PostgreSQL, JDBC/JDBI, React
- Hands-on Entwicklung zentraler Backend-Komponenten und kritischer Systemfunktionen
- Verantwortung für Engineering und Systemarchitektur eines PropTech-Startups von MVP bis Produktivbetrieb
- Migration des Backends von Kotlin auf Java (Spring Boot) zur Verbesserung von Wartbarkeit und Entwicklungsgeschwindigkeit
- Konzeption und Umsetzung einer End-to-End-Plattform für den Bau vermietbarer Immobilien (Java und React)
- Aufbau von Entwicklungsprozessen, CI/CD-Pipelines und containerisierten Deployments auf der Google Cloud
- Beteiligung am Unternehmen (Equity) als Anerkennung des Beitrags zur Produktbasis
- Technologien: Java 11-21, Spring, Thymeleaf, Google Cloud, PostgreSQL, JDBC/JDBI, React
- Designed and implemented new microservices, migrated legacy code to the modern Spring Boot stack.
- Improved performance and reduced technical debt in a high-growth fintech environment.
- Tech: Java 8, MySQL, REST (Jersey2), Docker, GitLab CI/CD
- Konzeption und Implementierung neuer Microservices
- Migration von Legacy-Code auf einen modernen Spring-Boot-Stack
- Performance-Optimierung und Reduktion technischer Schulden in einem stark wachsenden FinTech-Umfeld
- Technologien: Java 8, MySQL, REST (Jersey2), Docker, GitLab CI/CD