Dennis Kühn, Developer in Berlin, Germany
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Dennis Kühn

Verified Expert  in Engineering

Back-end Developer

Berlin, Germany
Toptal Member Since
July 26, 2021

Dennis is a software engineer with more than 15 years of experience, primarily in back-end development with an expert grasp of Java and related technologies. However, Dennis's work is not limited to any specific technology. Whatever tech the project requires, you can trust that his code will be well structured and scalable, thoroughly tested, and generally be well implemented. Dennis is passionate about creating sustainable, simple, and elegant solutions.


A Logistics Company (Self-employed)
Java, Spring Boot, OpenShift, Angular, PostgreSQL
A Musical Instrument Manufacturer (Self-employed)
AVR (8-bit MCU), Embedded C++, RS485, I2C, Serial Peripheral Interface (SPI)...
Equal Experts (Self-employed)
Java, Spring Boot, Elasticsearch, Angular, Oracle RDBMS, Kubernetes, Helm...




Preferred Environment

MacOS, IntelliJ IDEA

The most amazing...

...task I've worked on so far was creating a compiler for porting a legacy C codebase to Java.

Work Experience

Full-stack Developer

2021 - PRESENT
A Logistics Company (Self-employed)
  • Created a tool for managing contact information related to communication channels.
  • Connected with the business experts to find the most usable solution.
  • Developed a persistence solution that supports relational access to heterogeneous data structures.
  • Coached and mentored a junior developer to help them further their career.
Technologies: Java, Spring Boot, OpenShift, Angular, PostgreSQL

Software Engineer

2019 - PRESENT
A Musical Instrument Manufacturer (Self-employed)
  • Designed and implemented a distributed embedded system with real-time requirements.
  • Developed drivers for various peripheral modules, e.g., sensors, actuators, display, and so on.
  • Designed and created a high-throughput binary protocol.
  • Supported the company regarding digital transformation, software, hardware, and process-related topics.
Technologies: AVR (8-bit MCU), Embedded C++, RS485, I2C, Serial Peripheral Interface (SPI), MIDI, Python, Saleae

Software Engineer

2019 - 2021
Equal Experts (Self-employed)
  • Created a microservice-based research tool for a client in the music industry which required close cooperation with the domain experts, front-end development, and back-end development.
  • Implemented a migration tool based on complex domain logic.
  • Established the development, staging, and production infrastructure.
Technologies: Java, Spring Boot, Elasticsearch, Angular, Oracle RDBMS, Kubernetes, Helm, Prometheus, Grafana

Lead Developer (2017-2019) | Senior Java Engineer (2012-2017)

2012 - 2019
eBay | Brands4Friends
  • Managed a cross-functional development team that included back-end engineers, front-end engineers, and QA experts.
  • Implemented business requirements for eCommerce applications (a web shop, REST API, and so on) with a focus on robustness, maintainability, and security.
  • Designed and implemented a solution for integrating payment methods in a generic way. This included fine-grained tracking and monitoring of payment processes.
  • Worked continuously on the optimization of the technical platform and the development process, such as the transition from biweekly releases to continuous delivery.
  • Developed an authentication microservice supporting multiple access levels and federated OAuth2 login.
  • Created a microservice for inventory management with interfaces to ERP systems and marketplace APIs.
Technologies: Java, Spring, MySQL, Solr, Redis, Kubernetes, OAuth 2, Spring Security, Embedded Tomcat, Grafana

Senior Java Developer

2010 - 2012
  • Worked on the game server—implementing various single and multi-player games.
  • Created a compiler for porting a legacy C codebase to Java.
  • Implemented an algorithm for the distribution of profits.
Technologies: Java, JAX-RS, Enterprise Java Beans (EJB), JPA, Java Native Interface (JNI), C, JavaCC, Spring, GlassFish, PostgreSQL

Senior Software Engineer

2006 - 2010
Mediaworx Berlin AG
  • Developed multitenant web applications for a market leader in the tourism industry with configuration-based feature sets and layouts.
  • Implemented web services and web service clients (SOAP, REST).
  • Evaluated technologies for the company's service portfolio.
Technologies: Java, Apache Struts, Spring, Hibernate


An online shopping club where customers find highly discounted products.

As a lead developer, I was responsible for areas such as identity, payment services, and inventory management. Throughout my engagement, I contributed to modernizing the software design and architecture. Together with the operations team, I helped the company transition from a traditional release process to continuous delivery.
2000 - 2005

Diplom-Ingenieur (Master Equivalent) Degree in Media Computer Science

Hochschule der Medien - Stuttgart, Germany

MAY 2021 - MAY 2024

AWS Certified Cloud Practitioner

Amazon Web Services


Oracle Certified Professional, Java SE6 Programmer





IntelliJ IDEA, Solr, Grafana, JavaCC, Helm


Spring, Spring Security, JPA, OAuth 2, Apache Struts, Hibernate, Spring Boot, Angular


Spring Data, MySQL, Redis, Elasticsearch, PostgreSQL, Oracle RDBMS


Java, Python, C, JavaScript, SQL, TypeScript, Embedded C++


REST, Microservices, DevOps


MacOS, Docker, Kubernetes, Amazon Web Services (AWS), AVR (8-bit MCU), OpenShift


Software Development, Payment APIs, Distributed Systems, Web Security, Operating Systems, Networks, Embedded Tomcat, Java Native Interface (JNI), GlassFish, RS485, I2C, Serial Peripheral Interface (SPI), MIDI, Saleae, Prometheus, Enterprise Java Beans (EJB)

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