Arkadius Sikora-Senior Java Backend Developer | API & Integration Development | Cloud-Native Microservices | Regulated & KRITIS-Related
Check rate
Experience
AWS Pricing Platform / API & Integration Architecture
Porsche Digital
Development and evolutionary further development of a highly available, cloud-native microservice and integration architecture for dealer and retail processes in the Porsche Car Configurator.
Responsibilities
- Development of Java-/Kotlin-based backend, API, and integration components (Spring Boot)
- Integration of internal and external systems via REST/OpenAPI, GraphQL, Apache Kafka, and AWS SQS (synchronous and asynchronous)
- Implementation of stable, high-performance communication and data flows in a cloud-native platform architecture
- Processing of structured data formats (JSON, Protobuf, GraphQL schemas) based on existing API patterns
- Performance optimization of distributed microservices with reduced response times and higher operational stability
- Technical tests (unit, integration, and API tests) as well as error analysis in production-like environments
- AWS Infrastructure as Code with Terraform and AWS CDK
- CI/CD automation (build, test, and deployment pipelines) with GitHub Actions
- AI-supported feature implementation (GitHub Copilot Agent)
Label: Kotlin, Java 25, Spring Boot 4, Protobuf, TypeScript, AWS, Terraform, CDK, Apache Kafka, AWS SQS, REST/OpenAPI, GraphQL, JSON, PostgreSQL, Docker, GitHub Actions, Maven, Gradle, JUnit, Mockito, Testcontainers
KVS for TI Messenger (TI-M)
Bitmarck Holding GmbH
Account management system for the TI Messenger in the Gematik ecosystem: development of Java-/Kotlin-based microservices, connection of external systems, setup of the OpenShift/Kubernetes infrastructure. Multi-tenant platform (statutory health insurers) with the highest data protection and security requirements in a highly regulated healthcare environment.
Responsibilities
- Development of Java-/Kotlin-based backend services and software adapters (Java 21 / Spring Boot 3)
- Integration of external systems via REST/OpenAPI and SOAP (BitIAM, TI-M, Consent Keeper, Fdv, 3Scale)
- Implementation of API and integration components based on existing architecture, API, and design patterns
- Processing of structured data formats (JSON, XML/XSD) in the Gematik context
- Setup and operation of highly available OpenShift/Kubernetes platforms including Helm-based deployments
- CI/CD processes and platform standards (Jenkins) – build, test, deployment
- Error analysis, monitoring (Grafana), and production-like operational stabilization; migration of the dev cluster without interrupting ongoing development processes
- Responsibility for several productive microservices of a multi-tenant platform for statutory health insurers (GKVs)
- Technical leadership of a cross-functional DevOps team with end-to-end responsibility
Label: Java 21, Kotlin, Spring Boot 3, Spring Security 6, Keycloak, OAuth2, OIDC, OpenShift, Kubernetes, Docker, Helm-Charts, Jenkins, PostgreSQL, REST/OpenAPI, SOAP, JSON, XML/XSD, Liquibase, Grafana, 3Scale, JUnit, Mockito, Testcontainers
Architect; Senior Developer; Full Stack Developer; DevOps Lead
Bitmarck Holding GmbH
- Requirement engineering for Ombudsstelle and creation of technical user stories for EPA V3
- Handling of objections and revocations via mail and letter with high transaction mail volume
- Coordination with other teams on interfaces
- Design of a highly available, high-throughput solution on OpenShift with Java backend microservices
- Implementation and extension of microservices
- Infrastructure setup for deployment on OpenShift/Kubernetes including Jenkins pipelines
- Integration with BitIAM, TI-M Fachdienst, Consent Keeper and FDV
- Capture of requirements from DevOps operations and business units
- Continuous integration and Scrum practices
- Use cases: Kassenfusion, Opt-Out, Last Test, Widerspruchsmanagement
- Integration test automation and feature extensions including Spring Boot 3 updates
Senior Developer Full Stack; Product Owner
Signal Iduna Gruppe
- Implementation of microservices for backend and frontend
- Deployment on OpenShift
- Product responsibility and technical leadership
- Continuous integration and Scrum practices
Showcase Embedded Systems Dashboard
Comline SE
Development of a showcase dashboard for embedded systems with a serverless architecture on AWS.
Responsibilities
- Backend development and API design (Kotlin / AWS Lambda, GraphQL)
- Frontend development (React / TypeScript)
- Infrastructure as Code (AWS CDK, Terraform)
Label: Kotlin, React, TypeScript, AWS, AWS CDK, Terraform, AWS Lambda, AWS RDS, GraphQL, JSON, Docker
Senior Developer
Beutlhauser
Development of a large fleet management portal with an event-sourcing architecture (AxonFramework). Full-stack responsibility with end-to-end ownership for more than two years.
Responsibilities
- Full-stack and backend development (Java / Spring / Angular / TypeScript)
- Event-sourcing and event-driven architecture with AxonFramework
- Database design (MongoDB, MySQL, ElasticSearch)
- Building and optimizing CI/CD pipelines with GitLab CI and Docker (build, test, deployment)
- Deployment automation for AWS-based microservices, IAM integration (Keycloak)
Label: Java 8/9, Spring, Angular 7/8, TypeScript, AxonFramework, AWS, MongoDB, ElasticSearch, MySQL, JasperReports, GitLab CI, Docker, Keycloak
Senior Full Stack Developer
COMLINE Computer + Softwarelösungen AG
- Development of microservices for the CSP Java backend
- Mobile app development for Android and iOS
- Setup of cloud-service-platform infrastructure
Java Backend Developer
KION Group IT
- Software development with Java 8 and Criteria API
- Implementation of REST APIs with JSON
Development Engineer
Sophos Technology GmbH
- Frontend development with AngularJS and Bootstrap based on design specifications
- Backend development with Java 7 Spring Framework 4.0
- Support for Windows 10 Mobile MDM in the Sophos Cloud
- Integration of Sophos Mobile Security into the cloud
- Porting of the mobile component to Sophos Cloud V3
- Software development in Ruby for Sophos Cloud V2 mobile MDM on iOS and Android
- Behavior-driven development with RSpec
- Version control with Git and build automation via Bamboo
- Deployment on AWS
Application Support Engineer
Experian GmbH
- ITIL management and process optimization
- Incident management
- Support of email marketing services platform (CCMP)
- Introduction of new processes and enforcement of SLAs according to ITIL
- Automation scripts for backup storage
- Creation of IBM Crystal Clear Reports templates
System Administrator
Ceteq GmbH
- Provisioning of network infrastructure and installation of Opsi server
- DHCP configuration for PXE client workstations
- Integration of netboot products for Windows XP and Windows 7
- Automated software distribution setup
- Training staff on Opsi server maintenance
Test Specialist
E-Plus
- Review of service specification documents and application test scenarios/test cases
- Verification of document quality and completeness
- Provision of improvement recommendations
Software Developer; Software Tester; System Engineer
Software-Datenlieferant (TecDoc)
- Evaluation of interfaces and setup of test environment for Adobe BlazeDS AMF
- Development and integration of Groovy scripts in SoapUI for service testing and session handling
- Parameterization of scripts
- Integration with and evaluation of LoadUI for virtual user load testing
Student Assistant
RIF e.v.
- Hardware refurbishment and network setup
- Windows reconfiguration
- Server and network infrastructure installation
- Maintenance of projectors
Software Developer; System Engineer; System Administrator
TU Dortmund
- Java development of web portal and backend for cloud user management
- Setup and debugging of OpenNebula environments
- Code refactoring and bug fixing
- Design and implementation of IaaS environment based on OCCI and CDMI interfaces
- Architecture evaluation and test environment setup for OpenNebula
- Administration of hardware and software for high-performance IT infrastructure including DHCP, LDAP, KVM virtualization
- Maintenance of virtual infrastructure and documentation
Industry experience
See where this freelancer has spent most of their professional time.
Experienced in Insurance, Information Technology, Healthcare, Construction, Education, and Banking and Finance.
Business area experience
See which departments and functions this freelancer has contributed to most.
Experienced in Information Technology, Product Development, Operations, Project Management, and Quality Assurance.
Summary
Senior Java backend and integration developer with 13+ years of experience in developing Java-/Kotlin-based backend, API, and integration components. Focus on software adapters, REST/OpenAPI interfaces, messaging/event streaming (Apache Kafka), and cloud-native microservices in Kubernetes/OpenShift environments.
Several years of experience in regulated, security-sensitive, and KRITIS-related project environments (healthcare/Gematik, automotive, mobile security).
Skills
Focus Areas
- Software Architecture
- Software Development
- System Architecture
- Network Architecture
- Virtualization (Kvm, Xen, Esc)
- Cloud Computing (Opennebula, Vmware Vsphere, Occi, Cdmi)
- Storage (Nas, San)
- Administration (Ldap, Dhcp)
- Relational Databases, Nosql Databases
- Web Development
- Mobile App Development
Methodical Know-How
- Uml
- Structured Analysis
- Dynamic / Static Tests
- Specification Techniques Black-Box Test, White-Box Test
- Interface Tests
- Presentations
- Itil
- Process Models, Project Management (V-Model, Extreme Programming, Scrum, Kanban)
- Continuous Integration
- Continuous Delivery
Technical Know-How
- Microsoft Windows 10, 11
- Linux (Sles, Ubuntu, Centos)
- Macos
- Office Applications: Ms Word, Excel, Powerpoint, Visio, Project
- Databases: Mysql, Ms-Sql, Mariadb, Mongodb, Redis, Elasticsearch
- Programming Languages: Java, Javascript, Typescript, Groovy, Bash
- Software Version Control: Git, Subversion
- Software Firewall (Iptables)
- Ides: Intellij, Webstorm
- Web Servers: Apache Tomcat, Nginx
- Ticket System (Jira)
- Deployment Tools: Bamboo, Jenkins, Gitlab
- Web Services: Soap, Rest, Json, Xml
- Load And Performance Test Tools: Soapui, Loadui
- Microservices (Docker Container, Kubernetes)
- Vlan, Vpn, Vnc
- Html5 And Css, Bootstrap, Angular
- Aws, Openshift, Kubernetes
Languages
Education
University – details on request
Diploma in Computer Science, minor in Business Administration · Computer Science
Certifications & licenses
Statistics
Experience
Expertise
Qualifications
Profile
Frequently asked questions
Have questions? Find more information here.
Arkadius is based in Dortmund, Germany.
Arkadius speaks the following languages: German (Advanced), English (Advanced), Polish (Advanced).
Arkadius has at least 15 years of experience. During this time, Arkadius has worked in at least 15 different roles and for 14 different companies. The average length of individual experience is 1 year. Note that Arkadius may not have shared all experience and actually has more experience.
Based on recent experience, Arkadius would be well-suited for roles such as: AWS Pricing Platform / API & Integration Architecture, KVS for TI Messenger (TI-M), Architect; Senior Developer; Full Stack Developer; DevOps Lead.
Arkadius's most recent position is AWS Pricing Platform / API & Integration Architecture at Porsche Digital.
In recent years, Arkadius has worked for Porsche Digital, Bitmarck Holding GmbH, and Signal Iduna Gruppe.
Arkadius is most experienced in industries like Insurance, Information Technology, and Healthcare. Arkadius also has some experience in Construction, Education, and Banking and Finance.
Arkadius is most experienced in business areas like Information Technology, Product Development, and Operations. Arkadius also has some experience in Project Management and Quality Assurance.
Arkadius has recently worked in industries like Insurance, Healthcare, and Automotive.
Arkadius has recently worked in business areas like Information Technology, Product Development, and Operations.
Arkadius holds a Master in Computer Science from University – details on request.
Arkadius has 2 certificates. These include: ISTQB Certified Tester Foundation Level and Professional Scrum Master 1 (PSM I).
Arkadius is immediately available full-time for suitable projects.
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Calculated based on our freelancers’ daily rates as of 6 Sep 2026. Actual rates may vary depending on seniority level, experience, skill specialization, project complexity, and engagement length.
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