Jens Oberender - Freelance Java Developer / DevOps Engineer

Q: Where is Jens based?

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

Q: What languages does Jens speak?

Jens speaks the following languages: German (Native), English (Intermediate) .

Q: How many years of experience does Jens have?

Jens has at least 22 years of experience. During this time, Jens has worked in at least 9 different roles and for 18 different companies . The average length of individual experience is 1 year and 3 months . Note that Jens may not have shared all experience and actually has more experience.

Q: What is Jens's latest experience?

Jens's most recent position is Freelance Java Developer / DevOps Engineer at Undisclosed defense company .

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

In recent years, Jens has worked for Undisclosed defense company , Bosch , Zyres , CrossEngage , and MediaMarktSaturn .

Q: Which industries is Jens most experienced in?

Jens is most experienced in industries like Information Technology (IT) , Professional Services , and Energy . Jens also has some experience in Automotive , Aerospace and Defense , and Retail .

Q: Which business areas is Jens most experienced in?

Jens is most experienced in business areas like Information Technology (IT) , Product Development , and Customer Service . Jens also has some experience in Quality Assurance (QA) , Operations , and Research and Development (R&D) .

Q: Which industries has Jens worked in recently?

Jens has recently worked in industries like Automotive , Information Technology (IT) , and Aerospace and Defense .

Q: Which business areas has Jens worked in recently?

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

Recommended expert

Leipzig, Germany

Experience

Jun 2024 - Mar 2025

10 months

Remote

Freelance Java Developer / DevOps Engineer

Undisclosed defense company

Expanded OSGi modules in a complex communication solution
Debugged communication with Wireshark and remote debugging in the JENS test environment
Migrated tests from TestNG to JUnit 5 using Mockito and AssertJ
Updated vulnerable dependencies and improved code quality
Made changes to the Vaadin frontend
Increased test coverage

Sep 2022 - Apr 2024

1 year 8 months

Leipzig, Germany

Freelance Java Developer

Bosch

Improved data quality of an e-mobility platform
Analyzed data in MongoDB and performed various cleanups with Python scripts
Made adjustments and optimizations to several data-processing microservices
Handled supply chain security and upgraded dependency and JDK versions

Jun 2022 - Nov 2022

6 months

Freelance Java Developer

Zyres

Mar 2022 - Aug 2022

6 months

Freelance Java Developer

CrossEngage

Jul 2021 - Feb 2022

8 months

Freelance Java Developer

MediaMarktSaturn

Extended various microservices and deployed them to Google Cloud (GCP)
Updated Spring Boot and leveraged additional GCP features
Load tested a service and optimized it using Redis cache for higher loads
Introduced testing and code quality practices in the team

Apr 2021 - Jun 2021

3 months

Freelance Java Developer

1&1 Mail & Media Development & Technology GmbH

Further development of an existing web application in an 8-person Scrum team
Adaptation of microservices using TDD
Maintaining high coding standards with the help of Sonar

Feb 2021 - Apr 2021

3 months

Freelance Java Developer

The unbelievable Machine Company

Increase test coverage of an existing web application from 13% to 82%
Update dependencies using Maven and OWASP dependency checks

Aug 2020 - Jan 2021

6 months

Freelance Java Developer

Elinvar GmbH

Further development of various microservices for data import and processing
New development of a service for importing and archiving securities documents
Optimization of the build process regarding code coverage
Smooth migration of microservices to the Spring Boot framework

Feb 2020 - Jul 2020

6 months

Freelance Java Developer

IT Sonix Custom Development GmbH

Development of a billing system for an energy company in a five-person Scrum team
Refactoring components and adding new features
Improving automated quality control
Documenting business logic and securing it with appropriate tests

Aug 2019 - Nov 2019

4 months

Senior Java Developer / DevOps Engineer

Pamyra GmbH

Further development of a microservice architecture based on Spring Boot and Kubernetes
Expansion of logging and monitoring based on the ELK stack
Implementation of quality control and increase of test coverage
Refinement of the development process

May 2018 - Aug 2019

1 year 4 months

Senior Java Developer / Project Owner

Kiwigrid GmbH

Analyze requirements and develop appropriate projects with stakeholders
Evaluate different alerting and stream processing frameworks
Develop a driver to connect special customer hardware to the Energy Manager
Set up a cloud instance in Google Public Cloud using Kubernetes

Sep 2017 - Apr 2018

8 months

Lead Java Developer

cognitix GmbH

Lead an international team of 4 Java developers
Develop a system to process and visualize network traffic data
Prepare, normalize, and aggregate data with Kafka and Apache Flink
Coordinate with other teams and handle project management
Plan and assign tasks
Configure the build system, perform code analysis with SonarQube, and deploy with Docker

Feb 2015 - Aug 2017

2 years 7 months

Software Developer / DevOps Engineer

tarent solutions GmbH

Work on a legacy web application based on Velocity with a Lucene backend and Oracle database
Standardize code style and revise the release cycle
Provide crisis support through log file and performance analysis
Extend a Spring MVC web application and further develop the VerA.Web product
Revamp the deployment process using Docker and Ansible
Contribute to the company-wide build and Maven repository infrastructure
Provide DevOps support in Deutsche Telekom's Internet-of-Things project with deployment, monitoring, load, and performance tests
Participate in open source and software quality focus topics

Oct 2014 - Dec 2014

3 months

Software Developer

Aperto AG

Develop CMS (Magnolia) projects in a 7-person agile team
Customize a Maven archetype, improve the build process, and implement Selenium tests

Sep 2011 - Sep 2014

3 years 1 month

Software Developer

Pinguin AG

Work in a 5-person Scrum team with a product owner and designer
Develop an Android app using Maven, Android Annotations, and ActionBar Sherlock
Implement the REST backend in GlassFish with Spring and Jersey
Create OSGi server modules with Spring and Hibernate
Install and connect a search and logging server using ElasticSearch and Graylog2
Follow test-driven development and pair programming
Set up and maintain the build system (Jenkins, Nexus, Sonar, Git)
Collaborate with a team in Thailand through training, code reviews, and interface provisioning

May 2010 - Sep 2011

1 year 5 months

Software Developer

Prodato Integration Technologie GmbH

Refactoring and cleaning up a process management software and presenting it to the client
Migrating projects to Maven
Co-developing a JSF interface for an Oracle data warehouse
Short-term assignment in the SAP BW and BSP area at Siemens Healthcare

Sep 2007 - Apr 2010

2 years 8 months

Software Developer in the Development & Research Department

Keynote Sigos GmbH

Co-developed a Swing interface as well as performing bug analysis and fixes
Integrating a mapping interface in the project team
Migrating the backend from a TCL web server to a Tomcat servlet with XML protocol implementation
Introducing tests with JUnit and an automated build system
Switching the build tool from Ant to Maven and moving the code repositories to Git

Jun 2000 - Aug 2005

5 years 3 months

Working student and intern in the Support and IS&T Department

SUSE Linux GmbH

Linux support and server administration
PHP development with a MySQL database
Supporting the administration of the PKI infrastructure

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 Information Technology (17.5 years), Professional Services (2.5 years), Automotive (1.5 years), Energy (1.5 years), Aerospace and Defense (1 year), and Retail (0.5 years).

Information Technology

Professional Services

Automotive

Energy

Aerospace and Defense

Retail

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 (22 years), Product Development (14.5 years), Customer Service (5 years), Quality Assurance (4.5 years), Operations (3 years), and Research and Development (2.5 years).

Information Technology

Product Development

Customer Service

Quality Assurance

Operations

Research and Development

Skills

Java
Maven
Linux Administration
Spring Boot
Html & Css
Jenkins
Continuous Integration
Git
Junit 5
Mockito
Assertj
Lombok
Sonarqube
Test Driven Development
Mysql
Logging (Log4j2, Slf4j)
Shell Script
Ansible
Jenkins Pipeline
Github Actions
Gitlab Ci
Gradle
Google Public Cloud
Kibana
Docker
Jira/confluence
Python
Arduino And Microcontrollers
Rabbitmq
Mongodb
Elasticsearch
Kafka
Kubernetes
Openapi
Postgresql
Javascript
Apache Flink
Selenium
Vaadin
Very Good Java Skills
Very Good Linux Skills
Continuous Integration With Github Actions, Jenkins Or Gitlab Ci
Devops With Ansible, Docker, Kubernetes And Cloud (Gcp And Aws)
Database Knowledge (Especially Mysql And Postgresql)
Geographic Information Systems (Gis)
Driver Programming
Logging And Monitoring
Test-driven Development
Software Quality Assurance With Sonar, Owasp And Other Tools

Languages

German

Native

English

Intermediate

Education

Oct 2003 - Jun 2008

Georg-Simon-Ohm-Fachhochschule

Diploma in Computer Science (FH) · Computer Science · Nuremberg, Germany

Oct 2000 - Jun 2003

Friedrich-Alexander-Universität Erlangen-Nürnberg

Diploma in Computer Science (not completed) · Computer Science · Erlangen, Germany

Jan 1996 - Mar 1996

Student exchange

Melbourne, Australia

...and 2 more

Certifications & licenses

Java Web Hacking & Hardening

Maven

Novell Certified Linux Administrator

Linux Professional Institute LPIC-1

VHS course: Linux in the network

Profile

Created

June 2025

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Frequently asked questions

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

Where is Jens based?

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

What languages does Jens speak?

Jens speaks the following languages: German (Native), English (Intermediate).

How many years of experience does Jens have?

Jens has at least 22 years of experience. During this time, Jens has worked in at least 9 different roles and for 18 different companies. The average length of individual experience is 1 year and 3 months. Note that Jens may not have shared all experience and actually has more experience.

What roles would Jens be best suited for?

Based on recent experience, Jens would be well-suited for roles such as: Freelance Java Developer / DevOps Engineer, Freelance Java Developer, Senior Java Developer / DevOps Engineer.

What is Jens's latest experience?

Jens's most recent position is Freelance Java Developer / DevOps Engineer at Undisclosed defense company.

What companies has Jens worked for in recent years?

In recent years, Jens has worked for Undisclosed defense company, Bosch, Zyres, CrossEngage, and MediaMarktSaturn.

Which industries is Jens most experienced in?

Jens is most experienced in industries like Information Technology (IT), Professional Services, and Energy. Jens also has some experience in Automotive, Aerospace and Defense, and Retail.

Which business areas is Jens most experienced in?

Jens is most experienced in business areas like Information Technology (IT), Product Development, and Customer Service. Jens also has some experience in Quality Assurance (QA), Operations, and Research and Development (R&D).

Which industries has Jens worked in recently?

Jens has recently worked in industries like Automotive, Information Technology (IT), and Aerospace and Defense.

Which business areas has Jens worked in recently?

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

What is Jens's education?

Jens holds a Doctorate in Computer Science from Friedrich-Alexander-Universität Erlangen-Nürnberg.

Does Jens have any certificates?

Jens has 5 certificates. Among them, these include: Java Web Hacking & Hardening, Maven, and Novell Certified Linux Administrator.

What is the availability of Jens?

Jens is immediately available full-time for suitable projects.

What is the rate of Jens?

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