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 , 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 , Product Development , and Customer Service . Jens also has some experience in Quality Assurance , Operations , and Research and Development .

Q: Which industries has Jens worked in recently?

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

Q: Which business areas has Jens worked in recently?

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

Recommended expert

Leipzig, Germany

Check rate

Experience

Jun 2024 - Mar 2025

10 months

Remote

Freelance Java Developer / DevOps Engineer

Undisclosed defense company

Extension of OSGi modules in a complex communication solution
Debugging communication with Wireshark and remotely in the JENS test environment
Migration of tests from TestNG to JUnit 5 with Mockito and AssertJ
Updating vulnerable dependencies and improving code quality
Changes to the Vaadin frontend
Increasing test coverage

Sep 2022 - Apr 2024

1 year 8 months

Leipzig, Germany

Freelance Java Developer

Bosch

Improving data quality of an eMobility platform
Analyzing data in MongoDB and various cleanups with Python scripts
Adjustments and optimizations to multiple microservices for data processing
Supply chain security and upgrades of 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

Extending various microservices and deploying to Google Cloud (GCP)
Updating Spring Boot and using more GCP features
Load testing a service and optimizations using Redis cache for higher loads
Introducing tests and code quality 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-member Scrum team
Adjustment of microservices using TDD
Adherence to high coding standards with support from Sonar

Feb 2021 - Apr 2021

3 months

Freelance Java Developer

The unbelievable Machine Company

Increased test coverage of an existing web application from 13% to 82%
Updated 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
Development of a new 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

Developed a billing system for an energy company in a five-person Scrum team
Refactored components and added new features
Improved automated quality control
Documented business logic and secured 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
Expanded logging and monitoring using the ELK stack
Introduced quality control and increased test coverage
Refined the development process

May 2018 - Aug 2019

1 year 4 months

Senior Java Developer / Project Owner

Kiwigrid GmbH

Requirement analysis and project design with stakeholders
Evaluation of various alerting and stream-processing frameworks
Development of a driver to integrate special customer hardware with the Energy Manager
Deployment of a cloud instance in Google Public Cloud using Kubernetes

Sep 2017 - Apr 2018

8 months

Lead Java Developer

cognitix GmbH

Leading an international team of 4 Java developers
Development of a system for processing and visualizing network traffic information
Preparation, normalization, and aggregation of data with Kafka and Apache Flink
Coordination with other teams and project management
Planning and distribution of tasks
Configuration of the build system, code analysis with SonarQube, and deployment with Docker

Feb 2015 - Aug 2017

2 years 7 months

Software Developer / DevOps Engineer

tarent solutions GmbH

Working on a legacy web application based on Velocity with a Lucene engine and Oracle database
Standardizing code style and revamping the release cycle
Crisis support through log file and performance analysis
Extending a Spring MVC web application and further developing the VerA.Web product
Overhauling deployment with Docker and Ansible
Contributing to the company-wide build and Maven repository infrastructure
DevOps in Telekom's Internet of Things project with deployment, monitoring, load, and performance testing
Participation in the focus areas of open source and software quality

Oct 2014 - Dec 2014

3 months

Software Developer

Aperto AG

Developing CMS (Magnolia) projects in a 7-member agile team
Customizing a Maven archetype, improving the build process, and implementing Selenium tests

Sep 2011 - Sep 2014

3 years 1 month

Software Developer

Pinguin AG

Working in a 5-member Scrum team with a PO and a designer
Developing an Android app with Maven, Android Annotations, and ActionBar Sherlock
Implementing the REST backend in Glassfish using Spring and Jersey
Creating OSGi server modules with Spring and Hibernate
Installing and integrating a search and logging server with ElasticSearch and Graylog2
Test-driven development and pair programming
Setting up and operating the build system (Jenkins, Nexus, Sonar, Git)
Collaborating with a team in Thailand through training, code reviews, and providing interfaces

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 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-developing a Swing interface, including bug analysis and fixing
Integrating a map 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 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 MySQL database
Assisting with the administration of the PKI infrastructure

Industry Experience

See where this freelancer has spent most of their professional time.

Experienced in Information Technology, Professional Services, Automotive, Energy, Aerospace and Defense, and Retail.

Information Technology

Professional Services

Automotive

Energy

Aerospace and Defense

Retail

Business Area Experience

See which departments and functions this freelancer has contributed to most.

Experienced in Information Technology, Product Development, Customer Service, Quality Assurance, Operations, and Research and Development.

Information Technology

Product Development

Customer Service

Quality Assurance

Operations

Research and Development

Skills

Java
Maven
Linux Administration
Spring Boot
Html & Css
Jenkins
Continious 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 Knowledge
Continious Integration With Github Actions, Jenkins Or Gitlab Ci
Devops With Ansible, Docker, Kubernetes And Cloud (Gcp And Aws)
Database Skills (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 University Erlangen-Nuremberg

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

Statistics

Experience

Total positions 18

Experience in Information Technology 17.5 y

Avg length 1 y 3 m

Longest experience 5 y 2 m

Global Experience

Countries worked in 1 (Germany)

Primary country Germany

Expertise

Recent roles Freelance Java Developer / DevOps Engineer, Freelance Java Developer, Senior Java Developer / DevOps Engineer

Main industries Information Technology, Professional Services, Automotive

Main business areas Information Technology, Product Development, Customer Service

Qualifications

Highest degree Doctorate

Certifications earned 5

Profile

Created

June 2025

Last Update

June 2026

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Frequently asked questions

Have questions? Find more information here.

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, 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, Product Development, and Customer Service. Jens also has some experience in Quality Assurance, Operations, and Research and Development.

Which industries has Jens worked in recently?

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

Which business areas has Jens worked in recently?

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

What is Jens's education?

Jens holds a Doctorate in Computer Science from Friedrich-Alexander University Erlangen-Nuremberg.

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.