Jakarta EE Experts in Cologne

Hooman B.

Fullstack Developer

Last position:

Fullstack Developer at Möbel Roller GmbH

Further development of the existing e-commerce platform based on SAP Commerce (Hybris) to meet the growing demands of digital commerce.
Ensuring the scalability and performance of the backend, so the platform remained stable and efficient even under heavy user load.
Development and integration of new OCC REST APIs and services for modular extensions and flexible adjustments, to implement new features quickly.
Optimization of data flows and interfaces, which significantly improved platform efficiency and system performance.
Ensuring a maintainable and scalable code base by using Clean Code principles, proven design patterns, and a future-proof architecture.
Reduction of errors through extensive testing with JUnit, Mockito, and load tests with Gatling, supported by the introduction of automated test processes.
Improved system performance through targeted refactoring measures and efficient database queries, especially to handle peak loads.
Use of modern cloud and monitoring tools such as Kubernetes, Google Cloud Platform (GCP), and Grafana to ensure a stable and monitored infrastructure.
Clear improvement in efficiency, scalability, and reliability of the platform, which now meets the demands of a dynamic and growing e-commerce market.

Burhan D.

Experienced IT and AI Architect

Niederkassel

Last position:

Enterprise Architect & Solution Architect at DB Netz AG

With project PRIZMA, DB will modernize its infrastructure on the one hand, and develop a fail-safe IT landscape on the other hand, which can be restored quickly and securely in case of a disaster.

Capture current architectures of existing systems as well as methodical consulting and development of target architectures
Deepen and maintain the building plan / target IT landscape
Implement technical architecture concepts & architecture descriptions
Implement migration concepts for updating and further developing the platform and information systems
Assess submitted improvement suggestions as part of the project
Capability management: identify capability gaps, develop target visions, and support transformation planning within the enterprise architecture.
Create a compatibility matrix of the components in use and compare dependencies of specific versions
Create an IT concept for extending the platform with the following topics: hardware and software requirements, security, licensing, high availability, load balancing, backup & recovery, update strategy, monitoring integration, etc.
Coordinate with business architects as well as technical architects from the cross-functional architecture area of the PRISMA program for the topics (backup, Active Directory, monitoring, Citrix, and business applications ...)
Status meetings and alignment of project planning with the Release Train Engineer / Project Manager
Advise the Release Train Engineer / Project Manager in identifying project risks
Advise the System Architect Engineers in steering the implementation of the concept
Implement the IT concept
Document the infrastructure

Label: MS Project, LINUX, Windows, ORACLE, Java, REST, SharePoint, Microsoft Exchange, UML, Enterprise Architect, BPMN, AZURE, AWS, V-MODEL, Micro Service, VisualStudio, SAP S/4HANA, SCRUM(SAFE), ESB (TIBCO), Python, Innovator, LeanIX (TOGAF), Ansible, Ansible Tower, Ansible Automation, ROBOT, SpringBoot

Marc S.

Fullstack Engineer | Java & Spring Boot | Angular | System Integration

Leverkusen

Last position:

Fullstack Developer at PLANT-MY-TREE

PLANT-MY-TREE®-per-order

The application enables Shopify merchants to automatically place tree-planting orders for every incoming order. By integrating ecological contributions directly into the purchase process, the manual effort for tracking and billing reforestation initiatives is eliminated. The system increases transparency for end customers through real-time visualizations of the ecological impact directly in the storefront. The architecture is based on a modular monolith with Spring Boot in the backend and an integrated React app inside the Shopify admin area. The solution uses webhooks to capture order data in an event-driven way and integrates the weclapp ERP system for automated monthly invoicing. An app proxy mechanism provides dynamic statistics such as CO2 compensation and planted trees without any performance loss for the merchant shop.

Tasks:

Design of the modular software architecture based on Spring Modulith to ensure high maintainability
Development of the event-driven business logic for evaluating Shopify orders via webhooks
Implementation of automated invoicing by connecting the weclapp REST API
Building the frontend using React Router and Shopify App Bridge for native integration
Design of the database model and implementation of the persistence layer with JPA/Hibernate and Prisma
Integration of internationalization processes for global use in the frontend and email communication
Automation of deployment processes using Docker and GitLab CI/CD

Project skills: Java 25, Spring Boot, Spring Security, Spring Modulith, Hibernate, JPA, REST API, PostgreSQL, Maven, Liquibase, React, TypeScript, React Router, Vite, Node.js, Prisma, Zod, Docker, Docker Compose, GitLab CI/CD, Shopify CLI, Shopify App Bridge, Polaris, weclapp, i18next, Lombok, Vitest

Michael K.

Enterprise Architect, Lead Architect of the transformation program and coach

Last position:

Enterprise Architect, Lead Architect of the transformation program and coach at Swiss Ministry

Development of the overall architecture
Support for the respective workstreams in developing architectures in the areas of infrastructure, data centers, security, and network topology
Management of the architect pool
Support for program management in setting up the transformation project based on agile methods
Consideration of regulatory requirements for IT projects in the federal administration

Rainer L.

Senior IT Consultant, Senior Software Architect, Senior Software Developer, Senior DevOps Engineer

Last position:

Senior IT Consultant, Senior Software Architect, Senior Software Developer, Senior DevOps Engineer at Techniker Krankenkasse

Automation of the database major / minor releases for the TKeasy project
Concept for database major / minor release automation
As-is analysis
Evaluation of Redgate Flyway functionality
Concept creation
Products: Redgate Flyway, GitHub, Quest, Erwin Data Modeller, Oracle, Atlassian Jira, Atlassian Confluence
Skills: Docker, Continuous Delivery, Continuous Integration, Redgate Flyway, Major Releases, Minor Releases

Stefan M.

Installation Portal Server and Content Management Integration

Köln

Last position:

Bundesrechtsanwaltskammer

Design, planning and execution of complex acceptance tests for a document exchange platform for the German justice authorities.
Validation of decrypted and certificate-based message exchange via web platform, mobile app, and Java API.
Documentation of test cases, execution steps, and test results.
Technologies: Windows 11/10, Ubuntu, iOS, Android, Bash for Windows, Java 17, IntelliJ, Git, Jira, Confluence, Citrix Server, xJustiz standard implementation, specific justice software.

Allal K.

Java Senior Full Stack Developer

Frechen

Last position:

Java Senior Full Stack Developer at Insurance ÖRAG

Further development of a policy administration system (contract/claims) for the legal expenses insurer ÖRAG.
My role: Senior Software Developer.
The team consists of 12 developers.
Technologies used: Java 8/21, Java EE, Quarkus, WebLogic, JPA, RabbitMQ, JTA, CI, CD, Jenkins, DB2, Maven, Jenkins, GIT (bitbucket) later GitLab, Junit, Elasticsearch, Mockito, Jira, SonarQube, Scrum, React, Workflow
Migration and modernization of legacy systems: rewrote C and C++ code in Java to improve maintainability, scalability, and performance. Refactored Python into Java, including optimization and integration into modern architectures.
Study on the use of AI (Codex) for implementing a Java feature. The goal is to compare the time spent and productivity of AI-supported development with a classic implementation by a developer. The results should show how strongly the use of AI affects development time and efficiency.
Development of the following tariff calculators for the years 2024/2026: private, companies, doctors, farmers, owner-occupied G + H, landlords, traffic, club, top managers, sales representatives, special criminal law, savings bank, municipal, BayGT, doctors, Dehoga

Stanislaus S.

Security Consultant at Rohde & Schwarz AG

Monheim am Rhein

Last position:

Security Consultant at Rohde & Schwarz AG at Star Labs GmbH

Worked on FPGA enhanced network encryption device with secure boot, TPM2.0 and smart card integration for BSI approved usage with Post Quantum Cryptography
Developed and audited Linux drivers
Collaborated using GitLab, Gerrit, Confluence and Jira
Technologies: C, C++, Secure Boot

Markus G.

Full Stack Developer

Frechen

Last position:

Full Stack Developer at REWE Digital

A warehouse valuation system was reimplemented using Java, Spring Boot, and Camunda. The backend solution focuses on integration and batch calculations, the frontend on managing formulas and reviewing results.
Java 21
Spring Boot
JPA
Maven
REST
Kafka
PostgreSQL
DB2
Liquibase
Google Cloud Storage
Keycloak
GitLab CI/CD
Helm
Terragrunt
SonarQube
Angular
IntelliJ
JUnit 5
Mockito
Open API

Valeri M.

Associate Partner - Information Security Consulting

Bonn

Last position:

Associate Partner - Information Security Consulting at Insentis GmbH

Improvement of the Information Security Management System (ISMS) based on ISO 27001, NIS2, DORA, B3S, TISAX and BSI IT Baseline Protection
Conducting comprehensive gap analyses to identify gaps and derive action plans according to the above standards and regulations; management and KPIs
Data Loss Prevention strategy and implementation using MS Purview
Vulnerability and patch management, security monitoring
Risk analysis and threat modeling using the STRIDE methodology
Development of vendor risk assessments, implementation of risk classifications, conducting supplier assessments and implementing technical monitoring solutions (e.g. Security ScoreCard)
Securing cloud environments (AWS and Azure); expertise in CSPM/CNAPP (Wiz), cloud migration, secure CI/CD pipelines, container security and best practices in AWS, Azure and Office 365
Application security: penetration testing, DevSecOps, OWASP, pre-commit hooks, key and secret management, IDE plugins, static source code analysis, dependency checks, container scanning, vulnerability management, CIS benchmarks and compliance
Security assessment and hardening according to CIS benchmarks and cloud conformity in AWS, Office 365 and Azure

Alexander V.

Software Architect / Software Engineer / Tech Lead

Last position:

Senior DevOps / Platform Engineer at Kaufland e-commerce / real.digital (ex hitmeister.de)

Evolved the platform from bare-metal infrastructure with a monolithic PHP application to a hybrid Google Cloud architecture with Go microservices on Kubernetes
Managed and scaled a production infrastructure with 300+ VMs and dozens of clusters, including MySQL, PostgreSQL, MongoDB, RabbitMQ, Redis and Elasticsearch clusters
Designed architecture, deployment, monitoring, performance analysis, and upgrades for all platform services using Terraform and Ansible
Migrated observability systems from ELK and Prometheus to Datadog, managed with Terraform
Introduced Jenkins CI/CD with SonarQube integration and automated tests to speed up feedback cycles
Containerized the testing environment and implemented GitLab CI pipelines for Docker image builds, static code analysis, and infrastructure tests
Performed zero-downtime migrations of MySQL and MongoDB clusters to Google Cloud
Developed reusable Ansible roles for database clusters and automated data obfuscation for staging environments
Decomposed monolithic databases and migrated to microservice architectures
Built tools to detect and optimize slow queries in MySQL and MongoDB
Conducted online schema migrations with pt-online-schema-change without downtime windows
Developed internal Go applications for batch queries, GitLab-Jira integration, and MongoDB backup recovery
Technologies: Debian, Ubuntu, Alpine, Go, Bash, Python, PHP, SQL, GitLab CI, Jenkins, Drone CI, MySQL, MongoDB, PostgreSQL, Redis, Elasticsearch, RabbitMQ, Kafka, Docker, Kubernetes, Nomad, Ansible, Terraform, Grafana, ELK, Prometheus, Datadog, Nagios, Zabbix, Nginx, HAProxy, Vault, Helm, SonarQube, Filebeat, Auditbeat, Google Cloud, AWS

Vladimir M.

Developer

Brühl

Last position:

Developer at Financial services provider

Support and further development of a framework for developing applications in a banking association: DynS/OSPE
Migration of the framework to Java 11 and Java 17
Java8, Java11 and Java17, Spring, Spring-Batch, Spring WebServices, Spring-Security, Spring-Data, JPA, Hibernate, OpenSource libraries etc.
XML, JAXB, JSON, REST and SOAP services, DB2, Oracle, WebSphere or Liberty AS, FreeMaker, Junit, mock libraries, JaCoCo, Maven, IntelliJ, Eclipse, GitHub, SVN, Jira

Peter B.

Data Warehouse Consultant (Development and Analysis)

Köln

Last position:

Data Warehouse Consultant (Development and Analysis) at Atruvia AG

Developed and enhanced ETL loading jobs with IBM DataStage and optimized SQL in an IBM DB2 environment as part of the Agree21 data migration
Analyzed data quality and developed test procedures
Created PowerShell scripts and documented GIT deployment processes
Technologies: RedHat Linux, IBM DB2 with DBVisualizer, IBM InfoSphere DataStage 11.7, JIRA, TortoiseGIT, TortoiseSVN, PowerShell scripts

Jacqueline H.

Düsseldorf

Last position:

Kitchen Appliance Manufacturer

Setting up and enhancing an international subscription management system
Migrating and decommissioning a Hybris-SAP system and integrating Zuora
Implementing numerous interfaces to various systems (external and internal)
Setting up and improving monitoring with Grafana, Prometheus, and Databricks
Introducing logging with Loki
Implementing business requirements using jQuery, Thymeleaf, Spring Boot, Java, Go, and Python
Adjusting and extending the GitLab CI pipelines
Setting up and extending infrastructure as code with Terraform and ArgoCD on AWS
Setting up and running E2E and performance tests
Expanding the Databricks business intelligence solution to provide various KPIs
Responsibilities: Architecture, DevOps, development, unit tests, coaching employees and apprentices, E2E, smoke, and integration tests, agile methods consulting (Kanban, Scrum)
Technologies and methods: Java, Go, Kotlin, Node.js, Spring Boot, SOAP/REST, Quarkus, Thymeleaf, Vaadin, Slack, Jira, Confluence, IntelliJ, GitLab, SQS, Kafka, AWS, Kubernetes, Terraform, Maven, Gradle, GitLab CI, Databricks

Fabian Z.