Thomas W.-Senior Java Developer · Spring Boot · Legacy Modernization
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Experience
Senior Java Developer / Technical Lead
Logistics provider (shipping and parcel logistics)
Through 04/2022 via Capgemini, self-employed since 05/2022 via Mindcaptain Services OÜ.
- Overall technical responsibility for the business-critical Java core system (>1 Mio. LoC); no complete system outage since taking on this responsibility
- Data center migration: rebuilt Oracle WebLogic Server and the operating system from scratch; Oracle upgrade from 11g → 19c, including migration to Unicode (AL32UTF8)
- Developed and implemented a working modernization/upgrade path: migrated the entire legacy application to the latest Oracle WebLogic Server with updated Oracle ADF libraries
- Performance: sped up street segment imports from about 40 ms to 4 bis 5 ms per entry (factor of 8 bis 10) through caching (Redis) and database optimization
- Analyzed the cause and restored missing redress data despite shipments being physically present (the cause included user error in an upstream system); recovered data through data analysis, corrected the database, and restored accurate billing
- Microservices with Spring Boot and Kotlin (Java 8 bis 17) on Kubernetes, messaging via RabbitMQ; monitoring with Grafana and Prometheus; containerized deployments (Docker, Kubernetes)
- Smaller web projects: customer portal for tracking orders (React) and an internal Angular web app connected to the monolith, allowing system partners to upload their street directories
- Architecture decisions, technical roadmap, and business/IT stakeholder alignment; modernization without a big bang while the system remains in operation
- Leading another developer since 2024; code reviews, quality guidelines, knowledge transfer; coordinating subcontractors
Technologies: Java 6 (Legacy), Java 8 bis 17 (Microservices), Java EE/JEE, Oracle ADF, Oracle WebLogic Server, Oracle Database 11g/19c, PL/SQL, JPA/Hibernate, Spring Boot, Kotlin, RabbitMQ, Redis, Grafana, Prometheus, Docker, Kubernetes, Jenkins, GitHub Actions, GitLab, Git, Maven, Ant, Eclipse IDE, JUnit, SonarQube, Jira, REST, SSO/JWT, React, Angular
Software Engineer
Capgemini
- Project at a logistics provider starting in late 2019 (see above)
- Short-term assignment at a large German automotive manufacturer: API integration for the Chinese market using MuleSoft
Technologies: Java, MuleSoft, API integration, TypeScript, Next.js
Working Student, Research & Development
Diebold Nixdorf
- Smart Shelf project: developed the customer-facing React frontend for a kiosk terminal in a store, next to a smart shelf with scales in every compartment
- Customers sign in at the terminal scanner using a QR code from their account; when a scale detects an item being removed, the system sends the product to the frontend, which maintains a live shopping cart (Go, MongoDB, RabbitMQ)
Technologies: Java, Go, React, MongoDB, RabbitMQ, Next.js
Working Student, Software Development
dSPACE GmbH
- Developed a build analysis tool that creates a dependency graph between modules/components for impact analysis when changes are made; efficient in-memory data structure for graph searches
Technologies: C#, SonarQube
Industry experience
See where this freelancer has spent most of their professional time.
Experienced in Transportation, Information Technology, Automotive, and Retail.
Business area experience
See which departments and functions this freelancer has contributed to most.
Experienced in Information Technology and Product Development.
Summary
Senior Java Developer and System Owner focused on legacy modernization: technically responsible since late 2019 for the business-critical Java core system (>1 Mio. LoC) of a logistics provider, complemented by microservices with Spring Boot and Kotlin (Java 8 bis 17) on Kubernetes. Modernization without a big bang while the system remains in operation. Strengths: REST APIs, relational databases (Oracle 11g → 19c, PostgreSQL), JUnit tests and CI/CD (Jenkins, GitHub Actions, GitLab), code reviews, and leading another developer.
Skills
Backend
- Java 8 Bis 17 (Microservices)
- Spring Boot
- Rest Apis
- Microservices
- Kotlin
- Java Ee/Jee
- Jpa/Hibernate
- Java 6 (Legacy)
Modernization
- Legacy Modernization
- Data Migration
- Data Center Migration
- Oracle Weblogic Server
- Oracle Adf
Databases
- Postgresql
- Oracle Database 11g/19c
- Sql
- Pl/Sql
- Redis
- Mongodb
Quality & Ci/Cd
- Junit
- Ci/Cd
- Github Actions
- Gitlab
- Jenkins
- Sonarqube
- Code Reviews
- Test Automation
- Clean Code
Operations & Integration
- Docker
- Kubernetes
- Rabbitmq
- Grafana
- Prometheus
- Sso/Jwt
Architecture & Collaboration
- Software Architecture
- Requirements Engineering
- Architecture Decisions
- Knowledge Transfer
- Team Leadership
- Jira
Other
- Angular
- React
- Typescript
- Go
- C#
Basic Knowledge (Studies)
- Domain-Driven Design
- Soap
Languages
Education
University of Paderborn
M.Sc. · Computer Science · Paderborn, Germany
University of Paderborn
B.Sc. · Computer Science · Paderborn, Germany
Statistics
Experience
Global experience
Expertise
Qualifications
Frequently asked questions
Have questions? Find more information here.
Thomas is based in Tallinn, Estonia and can operate in on-site, hybrid, and remote work models.
Thomas speaks the following languages: German (Native), English (Advanced).
Thomas has at least 12 years of experience. During this time, Thomas has worked in at least 4 different roles and for 4 different companies. The average length of individual experience is 3 years and 11 months. Note that Thomas may not have shared all experience and actually has more experience.
Based on recent experience, Thomas would be well-suited for roles such as: Senior Java Developer / Technical Lead, Software Engineer, Working Student, Research & Development.
Thomas's most recent position is Senior Java Developer / Technical Lead at Logistics provider (shipping and parcel logistics).
In recent years, Thomas has worked for Logistics provider (shipping and parcel logistics) and Capgemini.
Thomas is most experienced in industries like Transportation, Information Technology, and Automotive. Thomas also has some experience in Retail.
Thomas is most experienced in business areas like Information Technology and Product Development.
Thomas has recently worked in industries like Transportation, Automotive, and Information Technology.
Thomas has recently worked in business areas like Information Technology and Product Development.
Thomas holds a Master in Computer Science from University of Paderborn and a Bachelor in Computer Science from University of Paderborn.
Thomas is immediately available full-time for suitable projects.
Daily rate distribution
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The median daily rate is the middle value of all daily rates — half of comparable freelancers charge less, half charge more. Unlike the average, it is barely affected by outliers.
Calculated based on our freelancers’ daily rates as of 7 Nov 2026. Actual rates may vary depending on seniority level, experience, skill specialization, project complexity, and engagement length.
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