JUnit Experts in Cologne
for reliable test automation, matched in minutes with vetted freelancersHire experts who design maintainable unit and integration tests, migrate JUnit 4 suites to JUnit 5, and connect testing with Spring Boot and CI pipelines. FRATCH matches you quickly and precisely with vetted, available freelancers.
Meet FRATCH Experts in Cologne, who have recently used JUnit
Hooman B.
Last position:
Fullstack Developer at Möbel Roller GmbH
- Further development of the existing e-commerce platform based on SAP Commerce (Hybris) to meet the growing demands of digital commerce.
- Ensuring the scalability and performance of the backend, so the platform remained stable and efficient even under heavy user load.
- Development and integration of new OCC REST APIs and services for modular extensions and flexible adjustments, to implement new features quickly.
- Optimization of data flows and interfaces, which significantly improved platform efficiency and system performance.
- Ensuring a maintainable and scalable code base by using Clean Code principles, proven design patterns, and a future-proof architecture.
- Reduction of errors through extensive testing with JUnit, Mockito, and load tests with Gatling, supported by the introduction of automated test processes.
- Improved system performance through targeted refactoring measures and efficient database queries, especially to handle peak loads.
- Use of modern cloud and monitoring tools such as Kubernetes, Google Cloud Platform (GCP), and Grafana to ensure a stable and monitored infrastructure.
- Clear improvement in efficiency, scalability, and reliability of the platform, which now meets the demands of a dynamic and growing e-commerce market.
Christoph S.
Last position:
Test Manager at Logistics
- Coordination and planning, execution, documentation, and analysis of test cases
- Development of test concepts considering best practices (e.g., test pyramid) with a focus on reliable, automatable test runs
- Implementation and maintenance of test cases according to the test concepts
- Technologies: Citrix Workspace, Shopify, Jira, Xray, MS Teams, MS SharePoint, Confluence, MS Office 365
Hassan A.
Last position:
DevOps & Observability Consultant at ALDI South (Albrecht's Discount)
- Supporting the DevOps team in Terraform-managed, multi-region AWS infrastructure to achieve environment parity.
- Developed end-to-end CI/CD pipelines using AWS CodePipeline, CodeBuild, and CodeDeploy, automating the build and deployment.
- Maintained pre- and post-deployment scripts to automate critical tasks such as database schema migrations and environment sanity checks.
- Implemented CI/CD flow specifically for hotfixes via separate Git branches, managing back-merge activities from feature branches to release branches to ensure code integrity through automated conflict resolution.
- Deployed a dedicated, lightweight sanity check application hosted cost-effectively on Azure Container Apps to run automated health and basic functional checks as a post-deployment activity triggered via pipeline.
- Investigated production incidents through code changes and AWS CloudWatch logs.
- Coordinated integration of Dynatrace APM and its APIs for monitoring purposes.
- Full stack QA strategist for a high-traffic e-commerce platform built on a layered architecture for the back-end testing of core platform services, especially the order management system in Zed and Glue layers.
- Managed automation activities, testing process, and refactoring practices.
- Responsible for framework migrations, setup, and training for new automation frameworks.
- Promoted a shift-left approach within the QA team and created the test concept.
- Participated in meetings with IT managers, business owners, product owners, and team members.
- Designed and implemented contract testing to validate API schema compatibility between the order management system and the Zed and Glue layers, reducing production-relevant breaking changes by approximately 3%.
- Led the migration to a multi-environment framework that enabled test execution across 4 country configurations from a single codebase.
- Integrated automated unit and functional tests directly into the GitLab CI/CD pipeline, reducing pipeline runtime by 32%.
- Coached and trained 5 QA engineers across Germany and Hungary in test automation, framework architecture, and best practices.
- Architected a layered backend test automation framework separating business logic, API request builders, and the database layer.
- Piloted AI-assisted testing with Playwright Agents, the Playwright MCP Server, and GitHub Copilot for automated test generation, execution, and self-healing Playwright scripts.
Marc S.
Last position:
Fullstack Developer at PLANT-MY-TREE
PLANT-MY-TREE®-per-order
The application enables Shopify merchants to automatically place tree-planting orders for every incoming order. By integrating ecological contributions directly into the purchase process, the manual effort for tracking and billing reforestation initiatives is eliminated. The system increases transparency for end customers through real-time visualizations of the ecological impact directly in the storefront. The architecture is based on a modular monolith with Spring Boot in the backend and an integrated React app inside the Shopify admin area. The solution uses webhooks to capture order data in an event-driven way and integrates the weclapp ERP system for automated monthly invoicing. An app proxy mechanism provides dynamic statistics such as CO2 compensation and planted trees without any performance loss for the merchant shop.
Tasks:
- Design of the modular software architecture based on Spring Modulith to ensure high maintainability
- Development of the event-driven business logic for evaluating Shopify orders via webhooks
- Implementation of automated invoicing by connecting the weclapp REST API
- Building the frontend using React Router and Shopify App Bridge for native integration
- Design of the database model and implementation of the persistence layer with JPA/Hibernate and Prisma
- Integration of internationalization processes for global use in the frontend and email communication
- Automation of deployment processes using Docker and GitLab CI/CD
Project skills: Java 25, Spring Boot, Spring Security, Spring Modulith, Hibernate, JPA, REST API, PostgreSQL, Maven, Liquibase, React, TypeScript, React Router, Vite, Node.js, Prisma, Zod, Docker, Docker Compose, GitLab CI/CD, Shopify CLI, Shopify App Bridge, Polaris, weclapp, i18next, Lombok, Vitest
Alexander K.
Last position:
Software Tester at Buhl Tax Service GmbH
- AI-assisted creation of test cases and test data
- Creation of test cases based on requirements
- Execution of manual tests
- Defect documentation, retesting and tracking
Technologies & Tools: SCRUM, Jira, Confluence, Zephyr Scale
Rainer L.
Last position:
Senior IT Consultant, Senior Software Architect, Senior Software Developer, Senior DevOps Engineer at Techniker Krankenkasse
Automation of the database major / minor releases for the TKeasy project
Concept for database major / minor release automation
As-is analysis
Evaluation of Redgate Flyway functionality
Concept creation
Products: Redgate Flyway, GitHub, Quest, Erwin Data Modeller, Oracle, Atlassian Jira, Atlassian Confluence
Skills: Docker, Continuous Delivery, Continuous Integration, Redgate Flyway, Major Releases, Minor Releases
Thomas P.
Last position:
Freelance Software Architect at Self-employed
Allal K.
Last position:
Java Senior Full Stack Developer at Insurance ÖRAG
- Further development of a policy administration system (contract/claims) for the legal expenses insurer ÖRAG.
- My role: Senior Software Developer.
- The team consists of 12 developers.
- Technologies used: Java 8/21, Java EE, Quarkus, WebLogic, JPA, RabbitMQ, JTA, CI, CD, Jenkins, DB2, Maven, Jenkins, GIT (bitbucket) later GitLab, Junit, Elasticsearch, Mockito, Jira, SonarQube, Scrum, React, Workflow
- Migration and modernization of legacy systems: rewrote C and C++ code in Java to improve maintainability, scalability, and performance. Refactored Python into Java, including optimization and integration into modern architectures.
- Study on the use of AI (Codex) for implementing a Java feature. The goal is to compare the time spent and productivity of AI-supported development with a classic implementation by a developer. The results should show how strongly the use of AI affects development time and efficiency.
- Development of the following tariff calculators for the years 2024/2026: private, companies, doctors, farmers, owner-occupied G + H, landlords, traffic, club, top managers, sales representatives, special criminal law, savings bank, municipal, BayGT, doctors, Dehoga
Markus G.
Last position:
Full Stack Developer at REWE Digital
- A warehouse valuation system was reimplemented using Java, Spring Boot, and Camunda. The backend solution focuses on integration and batch calculations, the frontend on managing formulas and reviewing results.
- Java 21
- Spring Boot
- JPA
- Maven
- REST
- Kafka
- PostgreSQL
- DB2
- Liquibase
- Google Cloud Storage
- Keycloak
- GitLab CI/CD
- Helm
- Terragrunt
- SonarQube
- Angular
- IntelliJ
- JUnit 5
- Mockito
- Open API
Jens H.
Last position:
#52 Test Manager in Safety-Critical Infrastructure at Telecommunications Company
- Network elements, network, operational and operator-related systems
- Supporting around 20 different products (managed agile)
- Requirements analysis and management (functional and non-functional)
- Test concept and planning (scope, test phases, effort, schedule, resources, organization, etc.)
- Aligning approach with clients and service providers
- Managing and assisting in creation of test cases for system, integration and end-to-end tests
- Guiding and supporting test execution
- Defect management and planning bug fixes with external providers
- Preparing and facilitating workshops
- Regular reporting and creating automated test reports
- Further development of agile testing methodology and configuration of supporting tools
- Conceptual support in developing a quality seal for rating product and service quality of internal and external providers
- Requirements engineering based on ISO/IEC 25010, Scrum, SaFE
- BMC Remedy, Atlassian Confluence, Atlassian Jira (including plugins Xray, Structure), Microsoft Office (incl. Visio), Obsidian, doxis document management system, Gitlab, Obsidian
Ayhan G.
Last position:
Senior QA Engineer / Test Automation Engineer / SDET at Rewe digital
Consulting, designing, and implementing the software testing lifecycle for multiple Android apps and backends Introducing test automation with Appium, SpringBootTest, RestAssured Setting up and managing emulators Developing an E2E library, an integration library, a Testcontainers library, and other libraries Developing, implementing, and advising on CI strategies Building the test environment with Testcontainers and virtualization Developing and implementing test cases for integration tests and end-to-end tests Establishing a maintainable test architecture with low entry barriers to simplify the creation of automated tests Some tools and technologies used: JUnit, RestAssured, Testcontainers, Kubedock, Appium, Android emulator, Jira Xray, Mockito, WireMock, Spring Framework, Kotlin
Predrag P.
Last position:
Test Developer | Test Automator at CreditReform
Technologies: Java 25, Selenium, Insomnia, SSO, GitLab, Jenkins, Docker, Kubernetes, Jira, IntelliJ, Nexus, Oracle, MariaDB, Spring Boot, Grafana, Concept Board, Vue.js, OpenAPI, Kotlin. Implementation, maintenance, and extension of automated end-to-end regression tests for UI and API interfaces. Appropriate and targeted test automation across multiple software products, including Java-based Windows applications. Automating business processes with Selenium, reset jobs, and DB import jobs, as well as creating test concepts, test case descriptions, and structured bug reporting.
Alexander V.
Last position:
Senior DevOps / Platform Engineer at Kaufland e-commerce / real.digital (ex hitmeister.de)
- Evolved the platform from bare-metal infrastructure with a monolithic PHP application to a hybrid Google Cloud architecture with Go microservices on Kubernetes
- Managed and scaled a production infrastructure with 300+ VMs and dozens of clusters, including MySQL, PostgreSQL, MongoDB, RabbitMQ, Redis and Elasticsearch clusters
- Designed architecture, deployment, monitoring, performance analysis, and upgrades for all platform services using Terraform and Ansible
- Migrated observability systems from ELK and Prometheus to Datadog, managed with Terraform
- Introduced Jenkins CI/CD with SonarQube integration and automated tests to speed up feedback cycles
- Containerized the testing environment and implemented GitLab CI pipelines for Docker image builds, static code analysis, and infrastructure tests
- Performed zero-downtime migrations of MySQL and MongoDB clusters to Google Cloud
- Developed reusable Ansible roles for database clusters and automated data obfuscation for staging environments
- Decomposed monolithic databases and migrated to microservice architectures
- Built tools to detect and optimize slow queries in MySQL and MongoDB
- Conducted online schema migrations with pt-online-schema-change without downtime windows
- Developed internal Go applications for batch queries, GitLab-Jira integration, and MongoDB backup recovery
- Technologies: Debian, Ubuntu, Alpine, Go, Bash, Python, PHP, SQL, GitLab CI, Jenkins, Drone CI, MySQL, MongoDB, PostgreSQL, Redis, Elasticsearch, RabbitMQ, Kafka, Docker, Kubernetes, Nomad, Ansible, Terraform, Grafana, ELK, Prometheus, Datadog, Nagios, Zabbix, Nginx, HAProxy, Vault, Helm, SonarQube, Filebeat, Auditbeat, Google Cloud, AWS
Vladimir M.
Last position:
Developer at Financial services provider
- Support and further development of a framework for developing applications in a banking association: DynS/OSPE
- Migration of the framework to Java 11 and Java 17
- Java8, Java11 and Java17, Spring, Spring-Batch, Spring WebServices, Spring-Security, Spring-Data, JPA, Hibernate, OpenSource libraries etc.
- XML, JAXB, JSON, REST and SOAP services, DB2, Oracle, WebSphere or Liberty AS, FreeMaker, Junit, mock libraries, JaCoCo, Maven, IntelliJ, Eclipse, GitHub, SVN, Jira
Louis N.
Last position:
Specialist in Adobe Experience Manager & Microservices at Nguenkam Consulting & Engineering
Java 11/21
Springboot
Swagger/OpenApi
Azure Pipelines
Trivy Integration
Apache Sling
OSGI
Java Content Repository (JCR)
Apache Jackrabbit Oak
Adobe HTL
GraphQL
Maven
GitLab
IntelliJ
Azure Cloud
Azure DevOps
Terraform
AEM specialist in the Scrum team
Development and deployment of microservices via Open API interfaces
Operation of microservices in the Azure Cloud
Implementation of AEM modules and integration with microservices
Member of the knowledge transfer team and a backend coordination team
Discover over 15,000 top freelancers
Statistics of experts using JUnit
Aggregated from the professional profiles of matched freelancers.
Experience
19 years
Position duration
1.7 years (Germany: 1.9 years)
Positions per freelancer
14 (Germany: 13)
Top business areas
Information Technology, Product Development, Quality Assurance
Top industries
Information Technology, Banking and Finance, Retail
Certification focus areas
Information Technology, Quality Assurance, Product Development
Bachelor's degree or higher
100% (Germany: 92%)
Master's degree or higher
69% (Germany: 51%)
Doctorate
13% (Germany: 6%)
Certifications per freelancer
3 (Germany: 2)
Most common languages
German, English, French
Speak two or more languages
100% (Germany: 96%)
Based on our profile pool as of 19 Sep 2026.
Daily rate distribution
The chart shows how the daily rates of freelancers in this technology in Cologne are distributed, based on recent contracts on our platform. Each bar covers a rate range — its height shows how many freelancers charge within that range.
Average rates of experts in Cologne using JUnit
Rates are based on recent contracts and do not include FRATCH margin.
The average daily rate is the mean of all daily rates from recent contracts of comparable freelancers on our platform.
The median daily rate is the middle value of all daily rates — half of comparable freelancers charge less, half charge more. Unlike the average, it is barely affected by outliers.
Calculated based on our freelancers’ daily rates as of 19 Sep 2026. Actual rates may vary depending on seniority level, experience, skill specialization, project complexity, and engagement length.
JUnit experts industry focus
See which industries our matched freelancers work in most often — every figure is calculated live from the freelancers on FRATCH.
- Information Technology (90%)
- Banking and Finance (52%)
- Retail (52%)
- Automotive (43%)
- Insurance (43%)
- Transportation (43%)
- Government and Administration (38%)
- Telecommunication (33%)
Please note that freelancers can work across multiple industries, so percentages overlap.
About the technology
What JUnit does
JUnit is a Java testing framework for verifying application behavior through repeatable automated tests. Teams use it to test business rules, services, data transformations and integration points before changes reach production. Its annotations, assertions and lifecycle controls give test suites a clear structure.
JUnit 5 ecosystem
Modern projects commonly use JUnit 5, whose platform separates test discovery from the Jupiter programming model. JUnit Jupiter provides the current programming and extension model, while the Vintage engine can run selected JUnit 4 tests during migration. Strong specialists also understand Maven or Gradle test configuration and IDE support.
Testing tasks
JUnit expertise appears across backend and enterprise Java work, from focused unit tests to broader integration coverage.
- Create readable tests for services, domain logic and REST components
- Configure parameterized, nested and dynamic tests
- Build test fixtures, test data and reusable extensions
- Stabilize suites that fail because of shared state or timing
- Connect tests with Maven, Gradle and continuous integration
When companies need help
Companies often bring in freelance expertise when a Java codebase has weak coverage, slow feedback or a difficult migration from JUnit 4 to JUnit 5. Specialists can establish a testing strategy alongside feature delivery, investigate flaky failures and prepare a suite for refactoring. Cologne teams may also value professionals who can work remotely while coordinating clearly with local product and engineering groups.
Adjacent skills
Effective JUnit work depends on more than writing assertions. Professionals should be comfortable with Java, object-oriented design, mocking and dependency injection, including Mockito and Spring Test where relevant. They may also use Testcontainers for realistic infrastructure checks, REST Assured for HTTP testing, and JaCoCo to review coverage trends without treating coverage as a quality guarantee.
Quality signals
Look for specialists who explain what each test protects and keep tests independent, deterministic and fast. They distinguish unit, integration and end-to-end boundaries instead of mocking every dependency or coupling tests to implementation details. A strong professional can review failure reports, improve test naming, document setup choices and show how the suite supports safer releases in a real Java codebase.
Frequently asked questions
Curious about JUnit? Here are the answers that come up again and again.
JUnit is used to automate tests for Java code, including domain logic, services, controllers and integration behavior. It helps teams detect regressions early and gives refactoring a safer, repeatable feedback loop.
JUnit 5 introduces the Jupiter programming model, a modular platform and a richer extension mechanism. JUnit 4 uses older annotations and runners, so migration usually involves updating imports, lifecycle methods, assertions and build configuration.
A strong JUnit specialist usually works confidently with Java, Maven or Gradle, mocking libraries such as Mockito and dependency injection frameworks such as Spring. Experience with Testcontainers, REST Assured and continuous integration is useful when tests cover infrastructure or HTTP boundaries.
The right level depends on the codebase, test debt and delivery risk rather than on a fixed number of years. A focused unit-test assignment may need someone who can work within existing conventions, while a JUnit 4 migration or flaky-suite investigation calls for deeper knowledge of test architecture and build tooling.
JUnit work is well suited to remote collaboration because tests, build files and failure reports can be reviewed in shared repositories. Teams in Cologne should agree on working language, review practices, access to test environments and regular overlap for diagnosing failures together.
JUnit is the natural choice when the application is written in Java and the team wants close integration with common build tools and IDEs. Other tools may suit browser journeys, contract testing or behavior-focused specifications better, but they often complement rather than replace JUnit.
Review whether JUnit tests are independent, deterministic, readable and focused on observable behavior. Good work explains the chosen test boundary, avoids excessive mocking, isolates external systems appropriately and keeps failures easy to diagnose.
JUnit Jupiter is the programming and extension model used to write tests on the JUnit 5 platform. JUnit 5 also includes the platform and other engines, so the names are related but do not describe exactly the same layer.
The average hourly rate of freelancers in Cologne, Germany who have used JUnit in their recent projects is 85 €, which corresponds to a daily rate of about 683 € based on an 8-hour working day.
Of the freelancers in Cologne, Germany who have used JUnit in their recent projects, 100% hold at least a Bachelor's degree, 69% hold at least a Master's degree, and 13% hold a doctorate.
On average, freelancers in Cologne, Germany who have used JUnit in their recent projects have 19 years of professional experience, with a single engagement typically lasting around 1.7 years.
The most common languages among freelancers in Cologne, Germany who have used JUnit in their recent projects are German (100%), English (100%), and French (19%).
The most common industries among freelancers in Cologne, Germany who have used JUnit in their recent projects are Information Technology (90%), Banking and Finance (52%), and Retail (52%).
The most common business areas among freelancers in Cologne, Germany who have used JUnit in their recent projects are Information Technology (100%), Product Development (81%), and Quality Assurance (81%).
Main locations of FRATCH Experts, who have recently used JUnit
Our freelancers and interim experts are at home across the DACH region — available on-site in the major business hubs or fully remote. Choose a location to discover matched specialists, local market insights and up-to-date availability.
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