Thomas Jarnot - Backend Developer, DevOps Engineer

Q: Where is Thomas based?

Thomas is based in Bonn, Germany and can operate in on-site , hybrid , and remote work models.

Q: What languages does Thomas speak?

Thomas speaks the following languages: German (Native), English (Advanced) .

Q: How many years of experience does Thomas have?

Thomas has at least 26 years of experience. During this time, Thomas has worked in at least 18 different roles and for 21 different companies . The average length of individual experience is 1 year and 2 months . Note that Thomas may not have shared all experience and actually has more experience.

Q: What is Thomas's latest experience?

Thomas's most recent position is Backend Developer, DevOps Engineer at AXA Digital Experience .

Q: What companies has Thomas worked for in recent years?

In recent years, Thomas has worked for AXA Digital Experience , REWE digital , Mesalvo , ALD Automotive , and REWE Systems .

Q: Which industries is Thomas most experienced in?

Thomas is most experienced in industries like Professional Services , Banking and Finance , and Retail . Thomas also has some experience in Information Technology (IT) , Automotive , and Insurance .

Q: Which business areas is Thomas most experienced in?

Thomas is most experienced in business areas like Information Technology (IT) , Product Development , and Quality Assurance (QA) . Thomas also has some experience in Customer Service and Business Intelligence .

Q: Which industries has Thomas worked in recently?

Thomas has recently worked in industries like Professional Services , Retail , and Information Technology (IT) .

Q: Which business areas has Thomas worked in recently?

Thomas has recently worked in business areas like Information Technology (IT) , Product Development , and Quality Assurance (QA) .

Recommended expert

Bonn, Germany

Experience

May 2024 - Jun 2025

1 year 2 months

Cologne, Germany

Backend Developer, DevOps Engineer

AXA Digital Experience

Further development, modularization, and technical modernization of the My AXA customer portal using Scrum.
Connecting new REST APIs to expand the digital product and service portfolio.
Splitting a monolithic application into clearly defined business responsibilities.
Continuous refactoring of complex code components to improve maintainability.
Supporting other teams in interface design and introducing WireMock for integration tests.
Standardizing caching and resilience by introducing Spring Cache and Resilience4J.
Cleaning up request validation according to JSR-170 and developing a simulation procedure.
Advancing the code generator to transform OpenAPI contracts into client libraries.
Developing dashboards and log file analyses using Loki and Grafana Cloud.
Monitoring and reporting of production and QA systems.
Techstack: Java 21, Spring Boot 3, REST, Resilience4J, Docker, OpenAPI, Grafana Cloud, Jenkins, Tekton, OpenShift, AWS, GitLab.

Aug 2023 - Apr 2024

9 months

Cologne, Germany

Solution Architect, Developer

REWE digital

Worked on the retail project REWE Bonus to design an in-house customer loyalty solution.
Analyzed historical data models and legacy backends in the area of promotion planning and discount management.
Identified non-product responsibilities and developed cleaned-up data structures.
Transformed a COBOL-driven record type interface (SEDAS) into a hierarchical domain model.
Designed and implemented the message model for promotional items based on Java and Spock.
Developed an efficient topic design for a Kafka-based messaging architecture.
Implemented Kafka producers/consumers based on Kotlin, Quarkus, and Spring Boot.
Advised on cloud-native, microservice, and data mesh architectures.
Documented architecture decisions and promoted a ubiquitous language.
Techstack: Java, Kotlin, Spring Boot, Quarkus, Apache Kafka, Docker, REST, GitLab, Spock, IBM DB2, Data Mesh, DDD.

Feb 2023 - Jul 2023

6 months

Freiburg im Breisgau, Germany

Software Developer, Coach

Mesalvo

Optimized the codebase for maintainability, test coverage, and modularization for digital medication management.
Built a Docker stack to support local development against MS SQL Server, SAP MaxDB, and MariaDB.
Migrated the monolithic codebase from Java 8 to Java 17.
Identified module boundaries and turned them into a model project based on Spring Boot 3 and REST (Level 3).
Developed the REST API with Spring REST Docs and documented it in a test-driven way.
Coached the team on Spring, REST, Docker, and testing strategies (Spock, BDD).
Set up the Azure deployment pipeline and implemented the Azure security concept.
Analyzed and optimized native Linux scripts by moving them into Docker-in-Docker stacks.
Techstack: Java 17, Groovy, Spring Boot 3, REST, WebFlux, Spock, Hibernate, Liquibase, Docker, Azure Cloud.

Jul 2022 - Dec 2022

6 months

Hamburg, Germany

Architect, Developer, Analyst

ALD Automotive

Greenfield project to digitize and automate customer processes like repossession and contract tiering.
Analyzed processes using domain storytelling and identified stakeholders.
Developed the REST API for customer services with Spring Boot and Kotlin.
Built the public customer frontend with React and TypeScript.
Developed a reactive client library based on Spring WebClient with automatic token refresh.
Managed AWS Kubernetes via SSH tunneling through Linux bastion hosts.
Set up the Azure deployment pipeline and implemented the security concept.
Integrated with Apache Kafka and conducted workshops on NATS/JetStream.
Techstack: Kotlin, Java, Spring Boot, WebFlux, Spock, Docker, Apache Kafka, React, TypeScript, AWS, Kubernetes.

Jan 2021 - Jun 2022

1 year 6 months

Cologne, Germany

Architect, Lead Developer

REWE Systems

Developed the KOS-Web framework to support the migration of microservices based on Spring Boot.
Designed a platform for digital vouchers integrating epay and PAYBACK (Project Kartenwelt).
Implemented asynchronous processing logic for POS transactions using REST services and DB2.
Built the Coupon World from scratch to provide up to 10 million pre-generated coupons in near real time.
Designed the platform following Domain-Driven Design principles (generation, redemption, validation, support).
Conducted analysis and risk assessment for the relaunch of the KOS-Payback platform towards Google Cloud and Kubernetes.
Designed an event-driven streaming architecture using Apache Kafka.
Introduced Kotlin, Groovy, and Spock (BDD) as well as Docker/Docker Compose to the development team.
Conducted coaching sessions on architecture topics, domain storytelling, and clean code principles.
Techstack: Kotlin, Java, Spring Boot, Apache Kafka, GitLab CI, Docker Compose, DB2, HATEOAS, Testcontainers.

Jul 2020 - Dec 2020

6 months

Berlin, Germany

Software Developer (Fullstack)

DHL IT-Services

Supported a cross-functional team on a logistics platform.
Automated the deletion of personal data in line with GDPR requirements.
Analyzed and decommissioned outdated services and migrated them to new Kotlin/Spring Boot backends.
Further developed backend services for alternative name spellings and digital copies.
Developed a frontend component based on Vue.js.
Assisted with incident analysis and technical modernization of existing systems.
Techstack: Kotlin, Java, Groovy, Spock, Spring Boot, Vue.js, Maven, Git, Team City, Oracle.

Jan 2019 - Jun 2020

1 year 6 months

Cologne, Germany

Software Developer (Fullstack), Domain Architect

REWE digital

Replaced the REWE online shop monolith with microservices built on Spring Boot and Kotlin.
Developed services for customer registration, login, and self-service features including password reset.
Redesigned a scalable data replication service for message-based synchronization via Kafka.
Implemented an authorization service based on Spring Security OAuth with Redis integration.
Established clean REST APIs and created a Kotlin DSL for HTTP requests.
Introduced Kotest (MockK) and aspect-oriented programming to encapsulate technical tasks.
Developed frontend components (BFF) based on Node.js, Next.js, and React.
Implemented Google reCAPTCHA Enterprise to secure the frontends.
Enhanced the monitoring platform using Kibana, Prometheus, and Grafana.
Adapted the CI pipeline to agent-based builds under Jenkins.
Techstack: Kotlin, Java, Spring Boot, Apache Kafka, PostgreSQL, Docker, Nomad, Consul, Grafana, React, Next.js.

Oct 2018 - Dec 2018

3 months

Cologne, Germany

Software Developer, Technical Coordinator

OBI digital

Responsible for coordinating, developing, and deploying the Product Information Service (microservice).
Prototyped the deployment stack based on Docker (Swarm mode) with an Nginx reverse proxy.
Set up the automated CI pipeline using Jenkins Declarative Pipeline.
Migrated the deployment stack to Google Cloud Platform (GKE/Kubernetes).
Established domain-driven design and consumer-driven contract testing (PACT).
Monitored runtime behavior using Spring Boot Admin.
Techstack: Spring Boot, REST, Docker, Jenkins, Git, Java, Groovy, Spock, React.

Apr 2018 - Sep 2018

6 months

Technical Lead, Software Developer, DevOps Engineer

ZEG

Redesigned the architecture of a CMS-based e-commerce platform for specialist retailers.
Promoted domain modeling and designed clean RESTful HTTP interfaces.
Implemented independent microservices for modern orchestration runtimes.
Shifted to reactive programming and non-blocking communication.
Externalized the frontend to React for improved performance.
Increased resilience using sidecar patterns (circuit breakers) and failover strategies.
Implemented monitoring, alerting, and self-healing mechanisms.
Migrated from centralized Bamboo agents to agile builds and infrastructure as code.
Advocated clean code principles and 12-factor app compliance within the team.
Techstack: Java 8/10, Magnolia CMS, Spring Boot 2, Docker, Kubernetes, GCP, Jenkins, Commercetools.

Jan 2018 - Mar 2018

3 months

Software Developer, Architect

REWE Digital

Developed the substitute service for synchronous identification of replacement items in fulfillment centers.
Implemented a dedicated Elasticsearch cluster for more-like-this searches.
Set up data storage using Elasticsearch (products) and JPA/CloudSQL (inventory).
Implemented data provisioning by consuming Kafka messages.
Ensured fault tolerance using Kubernetes and Hystrix (circuit breaker).
Documented the web API according to the OpenAPI 3.0 standard using Swagger.
Achieved REST compliance at Maturity Level 3 (HATEOAS).
Techstack: Spring Boot, Spring Data, Hibernate, Apache Kafka, Elasticsearch, Docker, Kubernetes, Swagger.

Mar 2017 - Dec 2017

10 months

Software Developer, Domain Architect, DevOps Engineer

CBC (Mediengruppe RTL)

Refactored an application landscape architecture into microservices using Spring Cloud and Docker.
Developed a public REST service to provide program data to network operators.
Implemented multi-stage security modules as Spring Boot starters for validation and authorization.
Ensured load balancing and availability using Eureka, Zuul, and Ribbon.
Built the Content Information Service to aggregate metadata following the entity-attribute-value pattern.
Decomposed the business architecture into scalable bounded contexts using domain-driven design.
Migrated standalone Tomcat servers to Spring Boot and extended JavaFX clients.
Techstack: Java, Spring Boot, Spring Cloud, Netflix OSS, Docker, Apache Kafka, RabbitMQ, MSSQL, JavaFX.

Oct 2016 - Feb 2017

5 months

Software Developer, Test Engineer

viaboxx GmbH

Developed the oncology information system NEOdb in a microservice architecture.
Implemented business modules (Patients, Accounts, Diagnoses, etc.) as bounded contexts.
Set up cross-service ID management and a database-per-service approach.
Built a filter resolution framework at the REST layer for cross-module sorting.
Configured SpEL-based rules for thresholds and data types in complex sequence data.
Integrated KeyCloak for token-based single sign-on.
Delivered the application stack as a Docker runtime for local testing scenarios.
Executed automated integration and UI tests with Cucumber and Selenium.
Complied with regulatory guidelines like GAMP (21 CFR Part 11).
Techstack: Spring Boot, Spring Data, Netflix OSS, Docker, Postgres, PL/pgSQL, KeyCloak, Cucumber, Selenium.

Jun 2016 - Sep 2016

4 months

Software Developer, Domain Architect

Deutsche Post Direkt GmbH

Redesigned a Java enterprise application for address rental and new customer acquisition.
Developed a high-performance frontend with an interactive map for area and radius selection.
Implemented interfaces for document upload/download and automated PDF delivery.
Set up a runtime scenario with multiple Java processes and Oracle RAC persistence.
Integrated engines for in-memory counting of address data via REST/JSON.
Techstack: Vaadin, Spring, REST, JSON, JEE, JBoss, Hibernate, Liquibase, Oracle, Maven, Jenkins.

Apr 2016 - May 2016

2 months

Software Development Coach

Haeger Consulting

Taught Java enterprise skills as part of the internal training project pathfinder.
Built a self-contained Spring Boot application including JPA persistence and a REST API.
Modeled the application domain and implemented Spring Data repositories.
Trained on REST semantics, HATEOAS, and the use of HTTP status codes.
Delivered a responsive frontend with Apache Wicket, Bootstrap, and HTML5.
Introduced agile methods, issue tracking, and code management with Git/Bitbucket.
Techstack: Spring Boot, Spring Data, JPA, Hibernate, Wicket, Bootstrap, Git, Maven.

Aug 2015 - Mar 2016

8 months

Software Developer (Fullstack), Technical Coordinator

Bank-Verlag GmbH

Connected eBanking components to external providers for card payment authorization.
Processed UTF-8 data into TLV structures and ISO8583 messages.
Developed the paydirekt registration application for ad-hoc participation during payment.
Implemented a complex workflow with two-factor authorization and HTTP redirects.
Enabled look-and-feel multitenancy and feature flags for different banks.
Set up a Selenium Grid environment for automated browser tests in the CI build.
Techstack: Java 8, Spring Boot, Wicket, Bootstrap, Jersey, Hibernate, DB2, Maven, Selenium, Cucumber.

Apr 2015 - Aug 2015

5 months

Software Developer (Fullstack)

Mazda Motors Deutschland GmbH

Developed an iPad-optimized prototype for displaying vehicle inventory.
Implemented progressive disclosure to improve user experience using jQuery-AJAX.
Used Apache Wicket as render engine, resource manager, and JSON provider.
Solved CORS issues using preflight requests and HTTP headers.
Implemented modern UI features like CSS transitions, infinite scrolling, and slideshows.
Techstack: Wicket, jQuery, Bootstrap, HTML5, Spring Boot, REST, Maven.

Oct 2014 - Mar 2015

6 months

Software Developer (Fullstack)

REWE Systems GmbH

Designed and implemented a big data dashboard to visualize statistical data.
Developed a web-based information system to manage placement elements in stores.
Built a JPA data layer, a REST interface, and batch processing.
Implemented security requirements such as SSL encryption and authorization concepts.
Provided SQL migration scripts for DB2 databases.
Techstack: Wicket, jQuery, Bootstrap, Spring, Hibernate, JPA, DB2, JBoss, Maven.

Mar 2014 - Sep 2014

7 months

Software Developer (Fullstack)

Deutsche Post IT Services GmbH

Migrated a call center application to Bootstrap 3 and introduced new user interaction concepts.
Switched to AJAX communication and REST-compliant resource mappings.
Implemented server-side validation using JSR-303 Bean Validation.
Developed custom jQuery-based controls and implemented front-end templates.
Optimized database queries and supported service layer design.
Advised on search engine integration, schema-less persistence, and the REST paradigm.
Techstack: Bootstrap, jQuery, AJAX, Spring MVC, Hibernate, JPA, Oracle WebLogic.

Oct 2013 - Feb 2014

5 months

Software Developer (Fullstack)

REWE Systems GmbH

Expanded the KAM/GFL business portal and refactored the persistence layer.
Built a component library based on Wicket, jQuery UI, and Bootstrap for the company.
Developed high-level components like Google Maps, smart tables, and content sliders.
Supported responsive design for a unified codebase across desktop and mobile.
Created an application prototype to present Payback data and customer dashboards.
Techstack: Wicket, Bootstrap, jQuery UI, Spring, Hibernate, Solr, DBVisualizer, Subversion.

May 2013 - Sep 2013

5 months

Software Developer (Fullstack)

HRS

Enhanced and modernized the eRFP hotel auction platform.
Extended Vaadin-based front ends and integrated new service components.
Introduced an event bus to decouple the corporate framework.
Migrated the front-end platform from Vaadin 6 to Vaadin 7.
Conducted refactorings to improve code quality.
Techstack: Vaadin 7, GWT, Spring, Hibernate, MySQL, MariaDB, Maven, Tomcat.

Oct 2012 - Apr 2013

7 months

Software Developer (Fullstack), Technical Consultant, Concept Author

Mercedes-Benz Trucks

Designed a content information system for delivering internationalized content (single source publishing).
Planned REST interfaces for integration into corporate infrastructure via SOA.
Designed a content repository based on ISO 639 to manage web and brochure content.
Developed a Web 2.0 admin frontend.
Re-engineered a web application for cost-effectiveness calculation (TCO Calculator).
Implemented financial math algorithms and interactive UI sliders.
Techstack: OSGi (Felix/Karaf), Jackrabbit/JCR, Vaadin, jQuery, Maven.

Jan 2001 - Oct 2012

11 years 10 months

Technical Lead J2EE, Platform Owner, Core Developer

Postbank Systems AG

Many years of development and expansion of the central J2EE multichannel banking platform (TMKP).
Technical lead for integrating SAP modules like Account Management and Transaction Banking.
Designed high-availability mechanisms (SLA Gold) and connected backend systems (BS2000, UTM, LDAP).
Modernized the platform by refactoring about 4000 classes and migrating to a new infrastructure.
Developed web frameworks and component libraries for online banking and call center clients.
Migrated complex Struts applications to Apache Wicket.
Implemented a web service gateway for 3D Secure mTan authentication.
Implemented a K-backup strategy (TXReloader) for recovery after system failures.
Developed J2EE z/OS integrations using the JCA standard.
Built test automation tools (data-driven testing) and acceptance workflow systems (IVTA).
Techstack: Java EE, Weblogic, SAP, Oracle RAC, Wicket, JAX-WS, JCA, CICS, Maven, Solaris.

Jan 2000 - Present

26 years 2 months

Germany

Initiator, Architect, Developer, DevOps Engineer

Filtech Exhibitions

Relaunched the domain-driven system landscape focusing on the Contacts, Companies, Exhibitors, and Invoicing modules.
Modularized with clear responsibilities and loose coupling through event-driven communication.
Designed and implemented core modules for partner and exhibitor management based on fine-grained microservices and MongoDB.
Introduced a diacritic search with Spring and MongoDB for use in an international environment.
Integrated an AI language model for querying structured data in natural language (NLP, RAG).
Implemented e-invoicing according to the ZUGFeRD standard and PDF/A3 format using iText and Project Mustang.
Conducted extensive system tests against the live stack including REST APIs, security, and messaging.
Upgraded to the latest releases of Spring Boot 3, MongoDB, Vaadin 23, and Kotlin.
Architecture style based on REST/HATEOAS, Domain-Driven Design, and event-driven architecture.
Techstack: Java 21, Kotlin, Spring Boot 3, REST, HATEOAS, MongoDB, NATS/JetStream, Spock (BDD Testing), Vaadin 23, iText-Core 9, Project Mustang, Groovy, Docker, NGINX, GitLab CI, Gradle, Maven.

Düsseldorf, Germany

Lead Developer

CCD • Congress Center Düsseldorf

Developed a location management system to manage building resources and halls.
Implemented a full-text search for room information and plan documents.
Implemented a query mechanism based on event parameters like room capacity and seating layout.
Techstack: Tomcat, Hibernate, Lucene, JDOM, Solaris.

Hamburg, Germany

Lead Developer, Technical Consultant

Promod Hamburg

Developed a talent and digital asset management system for modeling agencies.
Managed talent attributes and media assets (set cards, promotion media).
Implemented a casting feature to group talents with hyperlink dispatch.
Techstack: Tomcat, Hibernate, Lucene, JDOM, Linux.

Industries Experience

See where this freelancer has spent most of their professional time. Longer bars indicate deeper hands-on experience, while shorter ones reflect targeted or project-based work.

Experienced in Professional Services (26 years), Banking and Finance (12.5 years), Retail (5.5 years), Information Technology (4 years), Automotive (1.5 years), and Insurance (1 year).

Professional Services

Banking and Finance

Retail

Information Technology

Automotive

Insurance

Business Areas Experience

The graph below provides a cumulative view of the freelancer's experience across multiple business areas, calculated from completed and active engagements. It highlights the areas where the freelancer has most frequently contributed to planning, execution, and delivery of business outcomes.

Experienced in Information Technology (26 years), Product Development (26 years), Quality Assurance (26 years), Business Intelligence (0.5 years), and Customer Service (0.5 years).

Information Technology

Product Development

Quality Assurance

Business Intelligence

Customer Service

Summary

With over 20 years of professional experience as a software developer and architect, and after various renowned engagements with agencies, corporations, and external partners, Mr. Jarnot handles the diverse challenges between analysis, design, and implementation of modern information systems. Holistic design focused on top quality and reliability, as well as optimization for the target operational platform, are at the core of his work.

Mr. Jarnot relies on creatively combining established technologies like Java, Kotlin, Spring Boot, Docker, Spock Framework (BDD), Apache Kafka with long-tested concepts and architecture styles like REST/HATEOAS, Domain-Driven Design, event-driven architecture, CI/CD, 12-factor apps, as well as focuses on security, monitoring, and scalability.

As a senior full-stack developer and technical lead, he has successfully applied this knowledge for many years in interface design, integrating legacy backends, designing and implementing high-availability systems, refactoring monoliths, and numerous rollout projects in a dynamic and heterogeneous application environment.

He has many years of experience in agile software development under Scrum and Kanban for REWE Group, OBI digital, Postbank, HRS, DHL IT Services, Mercedes-Benz, RTL, Bank-Verlag, the AXA Group, among others, as an initiator of a congress and trade fair platform, as a coach for software development with Java, Kotlin, and Spring Boot, and as a contact person for modern architecture and design topics, rounding out his skill set.

Languages

German

Native

English

Advanced

Profile

Created

June 2025

Last Update

August 2025

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Frequently asked questions

Do you have questions? Here you can find further information.

Where is Thomas based?

Thomas is based in Bonn, Germany and can operate in on-site, hybrid, and remote work models.

What languages does Thomas speak?

Thomas speaks the following languages: German (Native), English (Advanced).

How many years of experience does Thomas have?

Thomas has at least 26 years of experience. During this time, Thomas has worked in at least 18 different roles and for 21 different companies. The average length of individual experience is 1 year and 2 months. Note that Thomas may not have shared all experience and actually has more experience.

What roles would Thomas be best suited for?

Based on recent experience, Thomas would be well-suited for roles such as: Backend Developer, DevOps Engineer, Solution Architect, Developer, Software Developer, Coach.

What is Thomas's latest experience?

Thomas's most recent position is Backend Developer, DevOps Engineer at AXA Digital Experience.

What companies has Thomas worked for in recent years?

In recent years, Thomas has worked for AXA Digital Experience, REWE digital, Mesalvo, ALD Automotive, and REWE Systems.

Which industries is Thomas most experienced in?

Thomas is most experienced in industries like Professional Services, Banking and Finance, and Retail. Thomas also has some experience in Information Technology (IT), Automotive, and Insurance.

Which business areas is Thomas most experienced in?

Thomas is most experienced in business areas like Information Technology (IT), Product Development, and Quality Assurance (QA). Thomas also has some experience in Customer Service and Business Intelligence.

Which industries has Thomas worked in recently?

Thomas has recently worked in industries like Professional Services, Retail, and Information Technology (IT).

Which business areas has Thomas worked in recently?

Thomas has recently worked in business areas like Information Technology (IT), Product Development, and Quality Assurance (QA).

What is the availability of Thomas?

The availability of Thomas needs to be confirmed.

What is the rate of Thomas?

Thomas's rate depends on the specific project requirements. Please use the Meet button on the profile to schedule a meeting and discuss the details.