Marcel Seifert-Lead Developer / Software Architect
Check rate
Experience
Lead Developer / Software Architect
Rezeptprüfstelle Duderstadt GmbH
Responsible for the redevelopment of a billing and validation software for prescriptions to fully check and analyze e-prescriptions for correctness (content, billing)
System consists of multiple contexts running as services (Docker containers):
Checking and processing data deliveries via FTP and email
Management of invoicing, clearings, deductions and offsets
Management and execution of validation rules and test sets
Analytics based on Metabase
Developer Stack: Kotlin, Vue 3 / Vuetify 3, ANTLR, Spring Boot 3, REST API, Gradle, Docker, GitLab, PostgreSQL, Kafka, Keycloak, Scrum, Grafana, Loki, Testcontainers, Prometheus
Beyond Chiefs GmbH
Design (analysis, PoC) and development of a platform for matching freelancers and employees with projects and jobs based on AI-powered skill analysis
Developer Stack: Java, Go, TypeScript, Node.js, Vue 3, Flowbite, Spring Boot, Spring AI, LLM, RAG, PostgresDB with vector extension, GitHub, Google Cloud, Kubernetes
Senior Developer
Vaillant GmbH
Further development of the B2B platform for integrating consumption data and controlling various heating systems (gas boilers, heat pumps) via public REST APIs for B2B partners
Platform consists of multiple microservices communicating synchronously (REST) and asynchronously (Kafka)
Data persistence in MongoDB or service-specific via Kafka Streams
Access control through Azure API Management and API specification described in the Azure Developer Portal
Developer Stack: Java 17–21, Go, Azure / APIM / Developer Portal, Spring Boot 2–3, Gradle, MongoDB (Atlas), Kafka / Kafka Streams, REST API / OpenAPI, GitHub / GitHub Actions, JWT / OAuth2, DevOps, Terraform, Instana, Grafana, Kibana, JUnit, Testcontainers, Mockito, Spring Boot Test, K6
OTTO GmbH
Implementation of a scalable microservice architecture with Java 17 and Spring Boot on AWS cloud for ingesting and processing product data (Excel, CSV, JSON) via web UI (React), FTP and REST API
Integration of product data into surrounding systems (e.g. marketplace) through asynchronous interfaces (Kafka)
Monitoring services with Grafana and Prometheus, logging with AWS CloudWatch, tracing with Elastic APM and OpenTelemetry
Developer Stack: Java 17, AWS, Kafka, MongoDB, PostgreSQL, React / MUI, Spring Boot, Gradle, Terraform, GitHub, OpenTelemetry, ElasticSearch, DevOps, Scrum, CI/CD, JUnit, Testcontainers, Mockito, Spring Boot Test, Testcafe
Feuerring GmbH
Development (part-time) and continuous improvement of a comprehensive CRM platform (contacts, email, calls, tasks, documents) as a modular monolith in Java 21 on Azure cloud with Spring Boot 3, Vue and Docker
Developer Stack: Java 21, Azure, Vue / Vuetify, Spring Boot 3, Gradle, PostgreSQL, GitHub, Docker, JUnit, Testcontainers, Mockito, Spring Boot Test
Intersoft AG
Further development of a new insurance platform for household contents and liability based on a microservice architecture with Java 11, Vue and Spring Boot in an on-premises cloud (Rancher, Kubernetes, Docker)
Developer Stack: Java 11, PostgreSQL, Oracle DB, Spring Boot, Vue / Vuetify, TypeScript, Kubernetes / Rancher, Gradle, Gitea, Jenkins, DevOps, Scrum, CI/CD, JUnit, Testcontainers, Mockito, Spring Boot Test, PowerMock
dealerdesk GmbH
Relaunch of the CRM platform for car dealers as a modulith in Java 11 and Spring Boot on Google Cloud
Launch of an online marketplace for electric vehicles as a standalone frontend with Vue and TypeScript with REST calls to the CRM platform
Developer Stack: Java 11, Spring Boot, Vue / Vuetify, TypeScript, Google Cloud, GitLab, JUnit, Testcontainers, Mockito, Spring Boot Test
Freelancer
e.kundenservice Netz GmbH (e.ON)
Creation of widgets for LoRa devices and dashboards to display indoor climate in buildings
Processing of IoT device data and integration within ThingsBoard
Developer Stack: Angular(JS), CSS, HTML, JavaScript, ThingsBoard
Freelancer
Fielmann AG
Providing self-service features for the registration process, order management and email sending based on a microservice landscape in AWS using .NET and C# as well as newer services in Kotlin and Spring Boot
Migration from .NET Core 2.1 to 3.1 / C# 8
Developer Stack: .NET Core / C#, Kotlin / Spring Boot, TypeScript / React, REST / DDD, Kafka, Concourse, Kubernetes / Helm / Docker, AWS, PostgreSQL, Scrum, Git, GitHub, SSL / TLS, JUnit, Testcontainers, Mockito, Spring Boot Test, TestCafe
Senior Java Server / Backend Developer (Freelancer)
Starfinanz GmbH
Integration of credit card and overdraft credit features and connection to the OSPEx bank interface in a Java 11 Spring Boot application for the Yomo banking app
Refactoring of the S-APP by moving business logic to Frontend-as-a-Service and Backend-as-a-Service
Developer Stack: REST / Swagger, Spring Boot 2, Java 8, Jenkins, Gradle, Scrum, Git, BitBucket, SSL / TLS, asymmetric encryption
Senior Software Developer
PLATH GmbH
Further development of the ICAS platform
Developer Stack: Eclipse RCP / OSGI, Spring, Servlet, Data Distribution Service (OMG, RTI), Java 8, Git
Senior Consultant
Swiss Life Deutschland Operations GmbH
Software architect for interfaces to back-office systems and building a new system landscape (Microservices, private on-premise cloud)
Representative at VDG New Development Technologies
Projects:
Application entry system (Spring Boot, RabbitMQ, ElasticStack, Cloud Foundry)
Evaluation of a PaaS environment
Document archive service for storing and retrieving internal archive systems (JAX-RS, JSON, JPA, EJB3, encryption with BouncyCastle)
Integration of a K&I system with surrounding legacy systems (JAX-RS, JSON, JPA, EJB3)
Harmonization of customer management systems
Migration interface for monitoring (Angular)
New development of a dashboard system based on portlets (JSR 286, Primefaces, JPA, Liferay 6)
Application Developer
Generali Schweiz
Development and enhancement of portlets for the broker portal (JSF, Portlets, JPA, JAX-WS, XML, WS-Security, SAML, SSL/TLS, gSOAP)
Projects:
Self-Service Portal
Data inquiry for commissions and contract data
Application Engineer (Java)
UBS Schweiz
Support and further development of the pending items system based on Java, PEGA (BPMN), EJB, IBM MQ, Struts
Project: PI (PendingItems) for Switzerland and International
Software Developer, from 2008-10-01 Team Lead Web Applications
tecis FDL AG
Support and further development of all web applications and the CMS system based on Lotus Domino; technical responsibility for the SitLap product
Projects:
Redesign of the SitLap product based on JSF / RichFaces and Hibernate
SitLap (Java, Struts, Apache FOP): financial planning tool including concept creation (PDF)
Business Report (Java, Struts): reporting and BI tool for sales
Excalibur (Java, Eclipse RCP, Hibernate): desktop application for capturing customer, advisor, application, and commission data
Industry experience
See where this freelancer has spent most of their professional time.
Experienced in Banking and Finance, Insurance, Information Technology, Retail, Healthcare, and Energy.
Business area experience
See which departments and functions this freelancer has contributed to most.
Experienced in Information Technology, Product Development, Business Intelligence, and Human Resources.
Skills
- Java
- Kotlin
- Type- / Javascript
- C#
- Go
- Html / Css / Sass
- Elasticsearch / Mongodb / Postresql
- Sql92
- Oracle Pl/Sql
- Apache Kafka
- Nunit / Junit / Wiremock / Rest Assured
- Angular / React / Vue
- Vuetify / Mui
- Git / Svn
- Jenkins / Concourse / Gitlab
- Maven / Gradle
- .Net Core
- Spring Boot / Spring Data / Spring Cloud
- Terraform
- Docker / Kubernetes
Languages
Education
tecis Service AG
IT specialist in application development · Hamburg, Germany
Certifications & licenses
Oracle Certified Master, Java EE 5 Enterprise Architect
Sun certified Web Developer (J2EE 1.4)
tecis Management Development Program
Statistics
Experience
Global experience
Expertise
Qualifications
Profile
Frequently asked questions
Have questions? Find more information here.
Marcel is based in Hamburg, Germany and can operate in on-site, hybrid, and remote work models.
Marcel speaks the following languages: German (Native), English (Advanced).
Marcel has at least 23 years of experience. During this time, Marcel has worked in at least 9 different roles and for 15 different companies. The average length of individual experience is 2 years and 7 months. Note that Marcel may not have shared all experience and actually has more experience.
Based on recent experience, Marcel would be well-suited for roles such as: Lead Developer / Software Architect, Senior Developer, Freelancer.
Marcel's most recent position is Lead Developer / Software Architect at Rezeptprüfstelle Duderstadt GmbH.
In recent years, Marcel has worked for Rezeptprüfstelle Duderstadt GmbH, Beyond Chiefs GmbH, Vaillant GmbH, OTTO GmbH, and Feuerring GmbH.
Marcel is most experienced in industries like Banking and Finance, Insurance, and Information Technology. Marcel also has some experience in Retail, Healthcare, and Energy.
Marcel is most experienced in business areas like Information Technology, Product Development, and Business Intelligence. Marcel also has some experience in Human Resources.
Marcel has recently worked in industries like Information Technology, Healthcare, and Retail.
Marcel has recently worked in business areas like Information Technology, Product Development, and Human Resources.
Marcel attended tecis Service AG for IT specialist in application development.
Marcel has 7 certificates. Among them, these include: ITIL V3 Foundation, OMG Certified UML Professional Fundamental, Oracle Certified Master, and Java EE 5 Enterprise Architect.
The availability of Marcel needs to be confirmed.
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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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