Projects

Over 10 years of freelance experience at leading companies — with projects from software development, system integration, process automation and technical architecture.

What I typically work on in projects

The projects listed here differ in industry, scope and technical environment. What they have in common is that they usually revolve around three core topics:

Digitalization Consulting

When processes have grown organically, become unclear or unnecessarily complex, clarity about workflows, bottlenecks and sensible next steps is needed first.

Learn more about Digitalization Consulting →

Process Automation

Many projects revolve around recurring workflows, system integration, data exchange and reducing manual work through clean technical solutions.

Learn more about Process Automation →

Software Architecture & Technical Project Management

When systems grow and technical projects become more complex, structure, sound decisions and a clear technical direction are needed.

Learn more about Architecture & Technical Project Management →

All services at a glance →

mkk – meine krankenkasse ·Enterprise Architecture Management · Freelance Software Engineer

11/2025 – present

— Delivered business-critical backend services in a regulated, high-availability KRITIS environment.
— Continued the integration of microservices with SAP LeanIX and Jira to strengthen architecture governance and visibility.
— Improved CI/CD pipelines and test automation to increase deployment reliability.
— Migrated long-running services to Java 17/21 and Spring Boot 3 to improve maintainability and platform readiness.

Java 17/21Spring Boot 3GraphQLOAuth2SAP LeanIXKubernetesPrometheusKibanaElasticSearchMicroservicesRESTDockerCI/CD

WineYoga · Freelance WordPress Developer

04/2025 – present

— Migrated an existing WooCommerce presence to a new domain and WordPress environment.
— Set up a reproducible local development environment using Docker and WP-CLI.
— Carried over existing plugins, themes and content fully into the new environment.
— Domain migration from wine-yoga.de to wineyoga.de (in progress).

WordPressWooCommercePHPWP-CLIDockerAstraSpectra

Zalando ·Logistics / Customs · Freelance Software Engineer

12/2024 – 12/2025

— Contributed to a distributed microservices architecture handling legally required customs declarations.
— Designed stable REST APIs consumed by multiple internal logistics systems.
— Integrated services through AWS S3-based workflows to ensure reliable data exchange.
— Supported the migration to Java 17/21 and Spring Boot 3 to improve maintainability and security.

KotlinJava 17/21Spring Boot 3KafkaAWSPostgreSQLKubernetesGradleGitHub CIOAuth2GrafanaKibanaElasticSearchPythonMicroservicesRESTDocker

mkk – meine krankenkasse ·Enterprise Architecture Management · Freelance Software Engineer

10/2024 – 12/2024

— Supported enterprise architecture initiatives in a regulated KRITIS environment.
— Integrated microservices with SAP LeanIX and Jira to improve transparency across systems and teams.
— Improved CI/CD pipelines and automated tests to strengthen delivery reliability.

Java 17/21Spring Boot 3GraphQLOAuth2SAP LeanIXKubernetesPrometheusKibanaElasticSearchMicroservicesRESTDockerCI/CD

Zalando ·Logistics · Freelance Software Engineer

07/2023 – 01/2024

— Developed REST APIs for managing and exposing warehouse working hours.
— Built backend services to import, persist and provide operational warehouse data.
— Developed a React-based internal frontend for operational users.
— Designed and optimized the underlying database schema to support reliable data handling.

KotlinJava 17Spring Boot 3ReactTypeScriptJavaScriptKafkaAWSPostgreSQLKubernetesOAuth2GrafanaKibanaElasticSearchPythonMicroservicesRESTDockerCI/CD

IONOS ·Customer Intelligence, Tracking · Freelance Software Engineer

08/2022 – 02/2023

— Developed REST APIs for processing customer tracking data.
— Contributed to a microservices architecture designed for high-volume event streams.
— Integrated messaging and persistence layers to support scalability and operational reliability.

Java 17Spring Boot 2KafkaMySQLPostgreSQLRedisOAuth2KubernetesMicroservicesRESTDockerCI/CD

Gorillas ·Foundation / Partnership Integration · Freelance Software Engineer

10/2021 – 08/2022

— Developed GraphQL and REST APIs for partner integrations.
— Contributed to the architecture of distributed systems across multiple business domains.
— Supported the migration from a monolithic application to a microservices architecture.
— Integrated external partner APIs into the platform.

KotlinSpring BootGraphQLOAuth2MongoDBPostgreSQLRedisKubernetesMicroservicesRESTDockerCI/CD

Daimler ·HR · Freelance Software Engineer

09/2021 – 10/2021

— Supported the go-live of a distributed web application for organizational charts.
— Delivered performance optimizations and production bug fixes during a critical rollout phase.

KotlinSpring BootPostgreSQLKubernetesDockerMicroservicesRESTCI/CD

Zalando ·Logistics · Freelance Software Engineer

01/2021 – 08/2021

— Contributed to distributed systems supporting warehouse operations.
— Migrated services from Java 8 to Java 11 and from Spring Boot 1 to Spring Boot 2.
— Set up automated tests and CI/CD pipelines to improve delivery quality.
— Implemented logging, monitoring and 24/7 alerting to strengthen production operations.

Java 8/11KotlinSpring BootAWSKafkaPostgreSQLKubernetesGrafanaKibanaElasticSearchOAuth2MicroservicesRESTDockerCI/CD

Bayes Esports ·Esports · Freelance Software Engineer

05/2020 – 12/2020

— Built a management service for controlling esports data consumption.
— Implemented new processing use cases for live esports data streams.
— Introduced production-ready logging, monitoring and alerting.

Java 8/11Spring BootAWSRabbitMQRedisPostgreSQLKubernetesGrafanaMicroservicesRESTDockerCI/CD

Zalando ·Logistics · Freelance Software Engineer

08/2019 – 04/2020

— Contributed to distributed warehouse control systems built on microservices.
— Supported the migration to Kubernetes and Spring Boot 2.
— Helped improve production stability in a large-scale operational environment.

Java 8KotlinSpring BootAWSKafkaPostgreSQLKubernetesGrafanaKibanaElasticSearchOAuth2MicroservicesRESTDockerCI/CD

ImmobilienScout24 ·Real Estate · Freelance Software Engineer

10/2018 – 07/2019

— Supported the migration from on-premise data centers to AWS.
— Contributed to the transition from monolithic systems to microservices.
— Developed and maintained business-critical backend services.

KotlinJava 8Spring BootAWSSpring CloudOracle SQLAngularJavaScriptKibanaElasticSearchOAuth2MicroservicesRESTDockerCI/CD

Klarna ·Banking · Freelance Software Engineer

05/2018 – 10/2018

— Contributed to a greenfield platform for processing credit card data.
— Developed microservices on AWS with a strong focus on security and scalability.
— Improved CI/CD pipelines and automated testing.

Java 8Spring BootAWSKafkaPostgreSQLKubernetesJenkinsSplunkMicroservicesRESTDockerCI/CD

Zalando ·Fulfillment · Freelance Software Engineer

11/2017 – 04/2018

— Developed microservices for fulfillment grouping and partner communication.
— Supported deployment, monitoring and production operations in a distributed environment.

Java 8KotlinSpring BootAWSKafkaCamundaKubernetesGrafanaKibanaElasticSearchOAuth2MicroservicesRESTDockerCI/CD

Market Logic Software ·Marketing · Freelance Software Engineer

07/2017 – 06/2018

— Developed backend services and system integrations.
— Implemented batch-processing workflows and persistent job scheduling.

Java 8Spring BootSpring BatchPostgreSQLElasticSearchKibanaKubernetesJenkinsGradleMicroservicesRESTDockerCI/CD

HRS Innovation Hub ·Tourism · Freelance Software Engineer

09/2016 – 05/2017

— Supported the migration of an e-commerce platform to a multi-tenant AWS-based solution.
— Developed REST APIs and backend services.

Java 8Spring BootAWSPostgreSQLElasticSearchKibanaGradleMicroservicesRESTDockerCI/CD

Lufthansa Industry Solutions ·Public Transportation · Software Engineer (permanent)

04/2015 – 08/2016

— Contributed to a user self-service portal for public transportation.
— Maintained and extended backend systems supporting sales and operations.

Java 7/8Java EEJSFOracle SQLWebservicesJBossTomEEJenkinsGradle

WineYoga

active

📍 Berlin · 1 yr

WordPressWooCommercePHPWP-CLIDockerAstraSpectra

04/2025 – present

— Migrated an existing WooCommerce presence to a new domain and WordPress environment.
— Set up a reproducible local development environment using Docker and WP-CLI.
— Carried over existing plugins, themes and content fully into the new environment.
— Domain migration from wine-yoga.de to wineyoga.de (in progress).

mkk – meine krankenkasse

active

📍 Berlin · 7 mo · 2 engagements

Java 17/21Spring Boot 3GraphQLOAuth2SAP LeanIXKubernetesPrometheusKibanaElasticSearchMicroservicesRESTDockerCI/CD

11/2025 – present Enterprise Architecture Management

— Delivered business-critical backend services in a regulated, high-availability KRITIS environment.
— Continued the integration of microservices with SAP LeanIX and Jira to strengthen architecture governance and visibility.
— Improved CI/CD pipelines and test automation to increase deployment reliability.
— Migrated long-running services to Java 17/21 and Spring Boot 3 to improve maintainability and platform readiness.

10/2024 – 12/2024 Enterprise Architecture Management

— Supported enterprise architecture initiatives in a regulated KRITIS environment.
— Integrated microservices with SAP LeanIX and Jira to improve transparency across systems and teams.
— Improved CI/CD pipelines and automated tests to strengthen delivery reliability.

Zalando

📍 Berlin · 3 yr 2 mo · 5 engagements

KotlinJava 17/21Spring Boot 3KafkaAWSPostgreSQLKubernetesGradleGitHub CIOAuth2GrafanaKibanaElasticSearchPythonMicroservicesRESTDockerJava 17ReactTypeScriptJavaScriptCI/CDJava 8/11Spring BootJava 8Camunda

12/2024 – 12/2025 Logistics / Customs

— Contributed to a distributed microservices architecture handling legally required customs declarations.
— Designed stable REST APIs consumed by multiple internal logistics systems.
— Integrated services through AWS S3-based workflows to ensure reliable data exchange.
— Supported the migration to Java 17/21 and Spring Boot 3 to improve maintainability and security.

07/2023 – 01/2024 Logistics

— Developed REST APIs for managing and exposing warehouse working hours.
— Built backend services to import, persist and provide operational warehouse data.
— Developed a React-based internal frontend for operational users.
— Designed and optimized the underlying database schema to support reliable data handling.

01/2021 – 08/2021 Logistics

— Contributed to distributed systems supporting warehouse operations.
— Migrated services from Java 8 to Java 11 and from Spring Boot 1 to Spring Boot 2.
— Set up automated tests and CI/CD pipelines to improve delivery quality.
— Implemented logging, monitoring and 24/7 alerting to strengthen production operations.

08/2019 – 04/2020 Logistics

— Contributed to distributed warehouse control systems built on microservices.
— Supported the migration to Kubernetes and Spring Boot 2.
— Helped improve production stability in a large-scale operational environment.

11/2017 – 04/2018 Fulfillment

— Developed microservices for fulfillment grouping and partner communication.
— Supported deployment, monitoring and production operations in a distributed environment.

IONOS

📍 Berlin · 6 mo

Java 17Spring Boot 2KafkaMySQLPostgreSQLRedisOAuth2KubernetesMicroservicesRESTDockerCI/CD

08/2022 – 02/2023 Customer Intelligence, Tracking

— Developed REST APIs for processing customer tracking data.
— Contributed to a microservices architecture designed for high-volume event streams.
— Integrated messaging and persistence layers to support scalability and operational reliability.

Gorillas

📍 Berlin · 10 mo

KotlinSpring BootGraphQLOAuth2MongoDBPostgreSQLRedisKubernetesMicroservicesRESTDockerCI/CD

10/2021 – 08/2022 Foundation / Partnership Integration

— Developed GraphQL and REST APIs for partner integrations.
— Contributed to the architecture of distributed systems across multiple business domains.
— Supported the migration from a monolithic application to a microservices architecture.
— Integrated external partner APIs into the platform.

Daimler

📍 Berlin · 1 mo

KotlinSpring BootPostgreSQLKubernetesDockerMicroservicesRESTCI/CD

09/2021 – 10/2021 HR

— Supported the go-live of a distributed web application for organizational charts.
— Delivered performance optimizations and production bug fixes during a critical rollout phase.

Bayes Esports

📍 Berlin · 7 mo

Java 8/11Spring BootAWSRabbitMQRedisPostgreSQLKubernetesGrafanaMicroservicesRESTDockerCI/CD

05/2020 – 12/2020 Esports

— Built a management service for controlling esports data consumption.
— Implemented new processing use cases for live esports data streams.
— Introduced production-ready logging, monitoring and alerting.

ImmobilienScout24

📍 Berlin · 9 mo

KotlinJava 8Spring BootAWSSpring CloudOracle SQLAngularJavaScriptKibanaElasticSearchOAuth2MicroservicesRESTDockerCI/CD

10/2018 – 07/2019 Real Estate

— Supported the migration from on-premise data centers to AWS.
— Contributed to the transition from monolithic systems to microservices.
— Developed and maintained business-critical backend services.

Klarna

📍 Berlin · 5 mo

Java 8Spring BootAWSKafkaPostgreSQLKubernetesJenkinsSplunkMicroservicesRESTDockerCI/CD

05/2018 – 10/2018 Banking

— Contributed to a greenfield platform for processing credit card data.
— Developed microservices on AWS with a strong focus on security and scalability.
— Improved CI/CD pipelines and automated testing.

Market Logic Software

📍 Berlin · 11 mo

Java 8Spring BootSpring BatchPostgreSQLElasticSearchKibanaKubernetesJenkinsGradleMicroservicesRESTDockerCI/CD

07/2017 – 06/2018 Marketing

— Developed backend services and system integrations.
— Implemented batch-processing workflows and persistent job scheduling.

HRS Innovation Hub

📍 Berlin · 8 mo

Java 8Spring BootAWSPostgreSQLElasticSearchKibanaGradleMicroservicesRESTDockerCI/CD

09/2016 – 05/2017 Tourism

— Supported the migration of an e-commerce platform to a multi-tenant AWS-based solution.
— Developed REST APIs and backend services.

Lufthansa Industry Solutions

📍 Berlin · 1 yr 4 mo

Java 7/8Java EEJSFOracle SQLWebservicesJBossTomEEJenkinsGradle

04/2015 – 08/2016 Public Transportation

— Contributed to a user self-service portal for public transportation.
— Maintained and extended backend systems supporting sales and operations.

Related services

Want to find out which type of support fits your situation? Here's an overview of my services or jump directly to the relevant detail:

Learn more about Digitalization Consulting → Learn more about Process Automation → Learn more about Architecture & Technical Project Management → All services at a glance →