Timo Külbel
Senior Fullstack Developer
Experience
Senior Fullstack Entwickler
Project: ZVFutureNow Industry: Banking
In a large banking association, the payment processing systems are being completely redeveloped. As part of my subproject, the payment operations are being rebuilt using stream processing.
- Design and development of stream processing for international payment transactions based on Kafka and Kafka Streams
- Development of various input formats for the business domain using Drools rules – dynamically adjusting validation rules
- Evaluation and comparison of various public cloud providers regarding their database offerings
Team size: 18 Technologies & Tools: Java 21, Kafka, Spring Boot, Google Cloud, SCDF, Kubernetes, PostgreSQL, Drools, Git, S3, MongoDB
Senior Fullstack-Developer
Project: International Claims System Industry: Insurance
In an insurance company, all central insurance systems are being redeveloped. My focus in this subproject is on the claims system that handles the processing of damage cases.
- Development and maintenance of a claims application that is extended per customer based on the Faktorzehn claims system. The technical stack is Java, Spring Boot, and Vaadin.
- Development of business processes using Camunda
- Development of asynchronous data interfaces to connected systems using Azure Service Bus
- Development of Grafana dashboards for production monitoring
Team size: 12 Technologies & Tools: Java 17, Spring Boot, Vaadin, Azure, Argo CD, Kubernetes, PostgreSQL, Camunda, Git, Faktorzehn, Azure Service Bus, Grafana, Octane
Team Lead Datenmigration
Project: Data Migration Tools in the Automotive Sector Industry: Leasing
Led development of migration tools for data transfer between multiple systems during the merger of two large leasing companies.
- Technical Product Owner for data migration tickets
- Supported management, business design, and business analysis in questions about functional or technical architecture
- Designed the data migration architecture for two applications
- Developed and maintained several backend applications and tools for data migration using Spring Boot, Kotlin, and Oracle
- Lead developer for a 12-member development team
Team size: 15 Technologies & Tools: Kotlin, Spring Boot, Oracle, Azure, Kotlin Exposed, Azure DevOps, Git, Jira
Senior Backend Entwickler und Data Engineering
Project: Digital Claims Reporting Industry: Reinsurance
In this reinsurance project, tools are built for claims search, including full-text search. We also create upload tools that let insurance clients submit claims via bulk imports. The submitted data is then transferred to data lakes or within a data mesh.
- Developed and maintained backend applications using Spring Boot, Spring WebFlux, and Kotlin
- Built data pipelines with Spark and Scala
- Optimized analytical queries and full-text searches
- Managed data workflows using Argo CD
- CI/CD with Azure DevOps
Team size: 6 Technologies & Tools: Kotlin, Spring Boot, Spring WebFlux, Azure, Cosmos DB, Azure Search, Argo CD, Databricks, Apache Spark, Scala, Azure DevOps, Git
Senior Software Entwickler
Project: Colibri Industry: Public Sector
COLIBRI is a payment system for unemployment benefits with an annual payout of about €15 billion. It currently runs on a three-tier architecture (presentation, logic, data) with CORBA and is written in C++. We are replacing C++ with Java.
- Used Java EE 7 technologies, especially the APIs: EJB, JTA, JAXB, JAX-RS, JPA, CDI, Bean Validation, Interceptors, Managed Beans
- Developed backend applications, microservices, and REST services
- Managed complex build processes (Maven, Git, Stash, Jenkins, etc.)
- Followed architecture and implementation guidelines
- Met IT security standards
- Debugged and profiled distributed applications
- Tested, integrated, and documented the migrated software components
Team size: 14 Technologies & Tools: Java EE 7, EJB, JTA, JAXB, JAX-RS, JPA, CDI, Bean Validation, Interceptors, Managed Beans, Microservices, REST Services, Maven, Git, Stash, Jenkins
Lead Developer Backend
Project: Social Network Industry: Non-Profit
Developed a social network for a sustainable mobile phone manufacturer.
- Built the backend component of the social network
- Integrated the system with Keycloak
- Developed the back-office GUI for the social network
- Designed the architecture for future expansion and development of the application
Team size: 12 (backend completely independent) Technologies & Tools: JHipster, Kotlin, Spring Boot, Angular, Keycloak, HATEOAS
Fullstack Developer and Product Owner
Project: E-Commerce-Capable Backend Systems in the Automotive Sector Industry: Leasing
Built a fully digital application process for a leasing company, including integration with digital marketplaces.
- Maintained the digital application flow
- Designed and developed a leasing and used car offering platform
- Developed various interfaces to external and internal partners
- Front-end development of the leasing configuration flow
- Product Owner for used-car leasing
Team size: 15 Technologies & Tools: Kotlin, Kubernetes, Azure, MongoDB (Cosmos), React, NATS, Redis, Camunda, React, PostgreSQL, Jira, Confluence
Technischer Teamlead
Project: Pricing Service Modernization Industry: Leasing
Rebuilt a pricing service as a microservice.
- Designed, developed, and operated the application
- Maintained user stories in Jira
- Developed backend pricing logic
- Implemented caching strategies for results
Team size: 4 Technologies & Tools: Java, Kubernetes, Azure, MongoDB, Redis
Senior Software Developer
Project: Notification Component Industry: Shipping Logistics
Enhanced a notification component.
- Developed and maintained a high-volume customer email notification component (messaging)
- Created a new push notification component
- Handled DevOps tasks like CI/CD setup, code, version, and release management
Team size: 8 Technologies & Tools: Java, OpenShift, Google Firebase, JMS, ActiveMQ, Oracle
Senior Software Developer
Project: Parcel Shop Finder Industry: Shipping Logistics
Rebuilt the parcel shop finder.
- Designed and developed microservices for parcel shop search
- Created automated load tests for the parcel shop finder using Gatling
- Performed DevOps tasks in OpenShift
- Followed Test-Driven Development (TDD)
Team size: 3 Technologies & Tools: Kotlin, OpenShift, Spring Boot, MongoDB, Grafana, Gatling
Entwicklung diverser Verwaltungstools für Unternehmen des Mittelstands
Examples:
- Backend for an online massage booking platform
- ERP for a plumbing company
- Warehouse management system for a moving company
Technologies & Tools: JHipster, Kotlin, Spring Boot, Angular, Keycloak, PostgreSQL
Lead Developer and Java Architect
Project: Fleet Management Software Industry: Automotive
Adapted and enhanced fleet management software for a fleet management service inside a leasing company.
- Deputy development manager (at the software service provider)
- Technical project lead for the client
- Lead developer of a sprint team
- Security officer for the software
- Data protection officer (at the software service provider)
- Responsible for interface development (mainly SOAP, REST), reporting, and business documents
- Ongoing improvements and bug fixes
- Created cost calculations in full-service areas
- Designed functional concepts for travel management billing
Team size: 7 Technologies & Tools: Java, Struts, Hibernate, Oracle, BIRT, SOAP, REST
Senior Developer
Project: Claims Management Component Industry: Insurance
Adapted and enhanced a claims management software for car insurance B2B damage notifications.
- Technical project lead for the client
- Ongoing improvements and bug fixes
- Responsible for interface development (mainly SOAP, REST)
Team size: 3 Technologies & Tools: Java, Struts, Hibernate, Oracle, BIRT, SOAP
Senior Developer
Project: International Fleet Management Rollout Industry: Fleet Management
A fleet management company expanded from domestic service to operations in 26 countries for a major international client.
- Developed various invoice importers
- Implemented country-specific adjustments in invoice processing
- Set up CI/CD build processes
- Used Test-Driven Development (TDD)
Team size: 6 Technologies & Tools: Java, Struts, Hibernate, Oracle, BIRT
Java Developer
Project: PDF Reports Industry: Credit Reporting Agency
Developed PDF reports (previously only ASCII text reports existed).
- Created PDF reports using iText
- Used Test-Driven Development (TDD)
- Designed the architecture for future extension and development
- Internationalized the report layouts
- Styled the PDF reports
Team size: 2 Technologies & Tools: Java, DB2, iText
Java Developer
Project: Development and Operation of Web Crawlers Industry: Credit Reporting Agency
Built web crawlers in the credit reporting field.
- Created a press crawler
- Operated and maintained crawlers for legal notices and company monitoring
- Developed a frontend for research staff to rate press crawler results
- Integrated crawler execution into UC4
Team size: 2 Technologies & Tools: Java, DB2, JSF, Lucene, UC4
Software Architect
Project: Analytical Campaign Management Industry: Non-Profit
Built a system for analytical campaign management for a non-profit organization.
- Responsible for software development and architecture of a ROLAP engine for analytical database marketing, focusing on target group segmentation and response analysis
- Coordinated test management with the client
- Supported the client’s target group definition within the ROLAP engine
- Designed the architecture for future extension and development
- Used Test-Driven Development (TDD)
Team size: 6 Technologies & Tools: Java, Struts, Hibernate, AspectJ, Oracle
E-Commerce für DIY / Textilhandel
Developed an ERP system for multichannel fulfillment. Built and integrated APIs for Shopify, Etsy, and Amazon shops. Set up email integration via SendGrid.
Technologies & Tools: JHipster, Kotlin, Spring Boot, Neo4j, DuckDB, Shopify API, Etsy API, Amazon API, Angular, GraphQL
Languages
Education
Diplom‐Wirtschaftsinformatiker · Business Informatics
Similar Freelancers
Discover other experts with similar qualifications and experience