AssertJ Experts in Germany
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Meet FRATCH Experts in Germany, who have recently used AssertJ
Fred H.
Last position:
Software Architect and Developer at Personal project
Recurring problem in my own AI-assisted projects: requirements analysis, use cases, and architecture decisions can be created quickly with AI support, but remain difficult to follow and scattered across Markdown files – knowledge is lost as soon as it is no longer in the context window. arknet turns requirements engineering and architecture knowledge into structured, verifiable data instead of plain text: requirements, use cases, and architecture decisions form a consistently linked knowledge graph, traceable from requirement to architecture decision – queryable by both people and AI agents. Technically based on RDF/OWL and a custom MCP server.
Result: Working MCP daemon, Docker image published automatically to GHCR, nine hexagonal modules, eleven ADRs (including an Open-Core licensing model). Requirements engineering and Ubiquitous Language hexagons are active. Public as a Community Edition under Apache-2.0 since 07/2026 (github.com/kogn-io/arknet), together with the Claude Code plugin and GHCR image; Open-Core model.
Label: Java, Maven, RDF, RDF4J, OWL, SPARQL, Model Context Protocol, Spring AI, Docker, GitHub, Git, Claude Code, Obsidian, DDD, Hexagonal Architecture, ArchUnit, JUnit, AssertJ, Interface Development, Software Architecture, Continuous Integration, Knowledge Management
Marcus B.
Last position:
Java and Quarkus Expert at Large German energy service provider
- Modernization of a large-scale Java enterprise application*
The project is modernizing a complex enterprise application that has grown over many years. The existing Spring-based legacy system runs on Java 8, OSGi, and Eclipse RCP and is being gradually migrated to a modern, maintainable architecture with Java 25 and Quarkus.
Marcus works on analysis, architecture, refactoring, and implementation. One focus is on untangling historically grown structures and dependencies and on building a clean, sustainable Java and Quarkus technology stack.
Tools & technologies: Java 8, Java 25, Quarkus, Hibernate ORM with Panache, EclipseLink, OSGi, Eclipse RCP, Maven, JUnit, Mockito, REST, JSON, Git, Eclipse IDE, IntelliJ IDEA Ultimate, Jira, Confluence
Jens O.
Last position:
Freelance Java Developer / DevOps Engineer at Unpublished defense company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
Celil U.
Last position:
ZÜRS Geo 2021 at adesso SE
- Frontend development
- Spring Boot
- Swagger
- Git
- GitLab
- SonarQube
- Docker
- Maven
- Java
- Angular
Tymofii S.
Last position:
Senior Backend Developer at Medavis
- Developed backend features for Modern RIS, a web-based Radiology Information System integrated with the existing Classic RIS via WebView.
- Worked on a modular Spring Boot backend covering clinical workflows such as appointments, examinations, patients, orders, reporting, billing, and inventory.
- Contributed to event-driven architecture using domain events to decouple workflows across backend modules.
- Implemented REST/OpenAPI endpoints, service-layer business logic, DTO mapping, validation, and integration points for the React frontend.
- Worked with PostgreSQL-backed domain models, Liquibase database changes, read/write model separation, and legacy RIS database structures.
- Integrated authentication and authorization flows using Keycloak and OAuth2.
- Added and maintained unit/integration tests using JUnit, Rest Assured, Testcontainers, and project-specific test utilities.
- Supported CI/CD and local development workflows using Maven, Docker Compose, Jenkins, and generated OpenAPI clients.
Tech stack: Java 21, Spring Boot 3.5, Maven, PostgreSQL, Liquibase, Keycloak, OAuth2, REST, OpenAPI/Springdoc, MapStruct, Lombok, Docker, Testcontainers, Jenkins.
Michael F.
Last position:
Freelancer, Solution Architect at Schufa AG
- Helped to design the AWS infrastructure, integrated services and backend architecture for use cases of an on-premise solution and partial migrations to AWS with fast response times
- Implemented automated AWS integration test suites
- Implemented mission-critical components and delivered them before the deadline in a production-ready state with operation and monitoring concepts
- This 2-month subproject was about building a data-intense pipeline (5 TB) to be enriched continuously with data
- Designed and implemented reusable AWS CDK constructs to be used across the company’s teams to enable faster onboarding with AWS
- Coached on AWS topics, distributed software patterns, security, domain-driven design, agile collaboration and documentation to improve performance and collaboration
- Technologies: AWS, GitHub Actions, ETL, monitoring, operations, TypeScript, Python, AWS CDK, CloudFormation, Java, Docker, AWS ECS, AWS Lambda, serverless, Jenkins, DevOps principles
Dirk B.
Last position:
Senior Software Developer at congstar
- Mobile app backend development for end-customer mobile management
- Implementation of authentication methods
- Conversion of a monolith into microservices
- Operational support
- Technologies: Kotlin, Quarkus, Microprofile, Jackson, MariaDB, Redis, JSON, XML, SOAP, Maven, Git, GitLab CI, Splunk, Grafana, Jenkins, Kubernetes, Helm, Terraform, Microservices
Dimitri S.
Last position:
Fullstack Developer, Integrator at Generali Deutschland Versicherung AG
- Developing automated build and deployment processes for the exclusive front office systems
- Integrating the front office systems into the IT infrastructure
- Developing innovative, user-friendly sales software for financial advisors
- Ensuring quality and flexibility through automation and working with CI/CD
- Working according to DevOps principles
- Operating the software together as a team in the AWS cloud and Azure cloud
- Deploying software artifacts to testing and production environments
- Maintaining the test environments
- Performing error analysis and providing information for further root cause analysis
- Maintaining and supporting the build pipeline
- Supporting load testing
- Coordinating the batch execution schedule with batch automation
- Creating concepts to further develop the software packaging process
- Building and delivering components to partners
- Developing GitLab and Jenkins pipelines for building, deploying and integrating components
- Automating processes with Spring Boot applications with a GUI (Thymeleaf, Angular 19)
- Developing RESTful Spring Boot applications with Kotlin and Angular 19, JDBC and REST accesses, data exchange via SFTP, XML (JAXB)
- Designing components using Domain-Driven Design (DDD)
- Replacing cmd and bash scripts with Spring Boot applications with a GUI
- Replacing Java 8 applications with JSP by Spring Boot 3 applications (Thymeleaf, Angular)
- Implementing frontend and backend authentication via Keycloak
- Writing JUnit tests with Mockito
- Increasing code coverage for SonarQube analysis
Rainer B.
Last position:
Senior Developer at RWE Trading
- Development of custom microservices in the power exchanges area based on Spring Boot 3 using PostgresQL, ActiveMQ, Kafka and S3
- Revision and re-implementation of legacy microservices (Scala / Akka) on Spring Boot 3
- DevOps tasks for running the microservices in an AWS runtime environment
- Senior role in the development area in collaboration with the internal client
Adil S.
Last position:
Mobile/Backend Developer at Freelance
- Built a cross-platform mobile application using React Native that interacts with IoT devices via RESTful APIs
- Implemented state management with Redux and integrated IoT-specific components for smooth data visualization and device control
- Developed RESTful APIs using Node.js and Express, utilizing MongoDB for scalable data storage
- Facilitated secure communication between the mobile app and IoT devices, enabling device onboarding, status monitoring, and control commands
- Implemented real-time data synchronization and optimized data flow to minimize latency
Orhan K.
Last position:
kv.digital GmbH
- Backend development work for appointment and doctor services, including the implementation of various requirements for managing doctor appointments.
- SCRUM/Kanban
- Java 21
- IntelliJ Idea
- SpringBoot (MVC, Data JPA, …)
- GIT
- Confluence
- JIRA
- Maven
- CI: Jenkins
- Docker
- ActiveMQ
- MariaDB
- Solr
- Liquibase
- Testcontainer
- JUnit5
- Mockito
Johannes E.
Last position:
Libri GmbH
- Operation and further development of the inventory system for booksellers (Quimus). It is an in-house development by Libri that is sold to customers as Software as a Service. The software is developed in an agile way by two developer teams (about 5 developers each). The software consists of around 25 Java microservices that mainly communicate via messaging and share a common Angular frontend. The application runs on Kubernetes in AWS.
- Technologies used: Java 17 & 21, Spring Boot 2 & 3, Hibernate, MySQL, Spring Cloud AWS, Lombok, AWS SQS, AWS SNS, AWS RDS, AWS S3, DynamoDB, Kubernetes, Docker, OpenSearch, Hibernate Search, Liquibase, Gradle, Terraform, Helm, GitLab CI, Keycloak OAuth2, TypeScript, Angular
- My focus until December 2023: Connecting additional POS systems to the inventory system. Connecting the data warehouse for report display. Extending existing features (goods receipts, invoicing, item management, ...). Operations and DevOps tasks.
- Focus from January 2024: Extracting the product search from the inventory system into a global service to use in other applications. Integrating the product search into the booksellers' online shops (also run by Libri). Importing and providing digital items in the product search.
Bela B.
Last position:
Full Stack Lead Developer, Backend Architect at Telefonica (O2)
The software supports the complete planning and approval of antennas for mobile telephony.
The system was implemented using an event-driven microservice architecture for cloud-native deployment with Quarkus on the backend, Kafka for communication, and Angular for the frontend. Services run on Kubernetes in Google Cloud. A special challenge was synchronizing with the legacy system still used by some users.
Ioan D.
Last position:
Senior Software Developer at ING
- Tribe Home, Product Area 4 - Customer in Life, Squad Cybertron.
- Analysis, design, development, and testing of new requirements for Optimmo, mortgage financing software.
- Analysis, design, development, and testing of the JEE application MWS kredit-baufi.
- Analysis, design, development, and testing of the Wicket Optimmo application.
- Analysis, design, development, and testing of kredit-baufi batch programs.
- Migration of kredit-baufi batches to RHEL9.
- CiL SCS consumer pacts with Finagle.
- CiL SCS touch point architecture integration.
- Team size: 10.
- Tools / Frameworks: OpenJDK Java 17, Kotlin 1.6.0, Azure, Jenkins, Stash, JEE, GitLab, JIRA, Confluence, git, Spring 6.0, Spring Cloud, Spring Data, Hibernate, JPA, JMS, Kafka, Oracle, PL/SQL, Red Hat Enterprise Linux (RHEL), Maven, REST, JBoss, IntelliJ IDEA, Wicket 9 and 10, Istio.
Jan M.
Last position:
Interface project at HR Solutions GmbH for Rhineland-Palatinate / BAMF at HR Solutions GmbH
- Developed an adapter from the central foreigner register to an internal application
- REST, JSON, OpenAPI, Spring Boot, Vue, Java, Maven, XAusländer
- Jira/Confluence/GitHub, Scrum+Kanban
Discover over 15,000 top freelancers
Statistics of experts using AssertJ
Aggregated from the professional profiles of matched freelancers.
Experience
21 years
Position duration
1.6 years
Positions per freelancer
16
Top business areas
Information Technology, Product Development, Quality Assurance
Top industries
Information Technology, Insurance, Automotive
Certification focus areas
Information Technology, Project Management, Product Development
Bachelor's degree or higher
92%
Master's degree or higher
85%
Doctorate
23%
Certifications per freelancer
2
Most common languages
German, English, Spanish
Speak two or more languages
100%
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 Germany 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 Germany using AssertJ
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.
AssertJ 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 (100%)
- Insurance (53%)
- Automotive (47%)
- Banking and Finance (47%)
- Professional Services (47%)
- Retail (47%)
- Energy (41%)
- Healthcare (41%)
Please note that freelancers can work across multiple industries, so percentages overlap.
About the technology
What AssertJ does
AssertJ is a Java assertion library for writing readable, fluent tests. Its chainable API makes expected values clear and produces detailed failure messages, helping teams verify objects, collections, exceptions, dates, files, and other results with less ambiguity.
Where it fits
AssertJ is commonly used with JUnit and other JVM testing tools. It works well in Spring Boot services, REST APIs, batch applications, libraries, and event-driven systems where tests need to express domain behavior rather than only compare raw values.
Ecosystem and tooling
Professionals often combine AssertJ with:
- JUnit Jupiter and the JUnit Platform
- Mockito for mocks and interaction checks
- Spring Boot test slices and integration tests
- Maven or Gradle build pipelines
- Java records, generics, and custom domain assertions
The surrounding toolchain determines how assertions are organized, executed, and reported in local and continuous integration environments.
Typical project work
Freelance specialists use AssertJ to create or improve test suites for services, controllers, repositories, messaging flows, and reusable libraries. Deliverables may include assertion refactoring, custom assertion classes, failure-message improvements, test utilities, and migration from less expressive assertion styles.
When companies need help
External expertise is useful when test suites are difficult to read, slow to change, or unreliable during refactoring. Common signals include:
- JUnit tests with unclear or repetitive assertions
- Weak failure messages that delay diagnosis
- A migration from older assertion libraries
- New Spring Boot modules without consistent test conventions
- A need to verify complex object graphs or collections
In Germany, remote collaboration is often practical, while teams may still prefer on-site workshops for test strategy and knowledge transfer.
What strong specialists bring
A strong AssertJ professional understands both the fluent API and the behavior under test. They choose precise assertions, avoid brittle implementation checks, use custom assertions when the domain warrants them, and keep tests independent and maintainable. They also know how to align AssertJ with JUnit, Mockito, build automation, and the team’s Java coding standards.
Frequently asked questions
Questions about AssertJ? Start with the answers below.
AssertJ is used to write fluent, readable assertions in automated Java tests. It supports detailed checks for values, objects, collections, exceptions, dates, files, and recursive structures, making failures easier to understand.
AssertJ usually offers a more fluent API and strong, context-rich failure messages than standard JUnit assertions. Compared with Hamcrest, its method chains and collection assertions can be easier to discover, though the best choice depends on the project’s existing conventions.
An AssertJ specialist should be comfortable with JUnit Jupiter, Java, Maven or Gradle, and test design. Experience with Mockito, Spring Boot testing, REST clients, parameterized tests, and continuous integration is also useful when assertions are part of a broader test suite.
A focused AssertJ task may only require solid Java and unit-testing knowledge. Larger refactoring or test strategy work calls for someone who can understand domain behavior, identify brittle assertions, design reusable test utilities, and improve failures without hiding defects.
Yes, AssertJ work is well suited to remote collaboration because test code, build results, and review feedback are easy to share. German teams should define repository access, review practices, working language, and availability for workshops before the engagement begins.
Ask an AssertJ specialist to explain how they would test collections, exceptions, nested objects, and changing domain models. Review whether their examples use clear assertions, useful failure messages, stable test boundaries, and minimal dependence on implementation details.
Yes, AssertJ can replace vague or repetitive assertion styles with readable fluent checks. A careful specialist should modernize incrementally, preserve test intent, improve diagnostics, and avoid changing production behavior while the suite is being refactored.
An AssertJ freelancer should first learn the project’s Java version, JUnit setup, build process, and domain vocabulary. In Germany, clarifying remote or on-site expectations and the team’s preferred communication language can prevent avoidable friction during reviews and workshops.
The average hourly rate of freelancers in Germany who have used AssertJ in their recent projects is 93 €, which corresponds to a daily rate of about 741 € based on an 8-hour working day.
Of the freelancers in Germany who have used AssertJ in their recent projects, 92% hold at least a Bachelor's degree, 85% hold at least a Master's degree, and 23% hold a doctorate.
On average, freelancers in Germany who have used AssertJ in their recent projects have 21 years of professional experience, with a single engagement typically lasting around 1.6 years.
The most common languages among freelancers in Germany who have used AssertJ in their recent projects are German (100%), English (94%), and Spanish (12%).
The most common industries among freelancers in Germany who have used AssertJ in their recent projects are Information Technology (100%), Insurance (53%), and Automotive (47%).
The most common business areas among freelancers in Germany who have used AssertJ in their recent projects are Information Technology (100%), Product Development (100%), and Quality Assurance (65%).
Main locations of FRATCH Experts, who have recently used AssertJ
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.
Berlin Hamburg Munich Cologne Frankfurt Stuttgart Dusseldorf Leipzig Dortmund Essen Bremen Dresden Hanover Nuremberg Request a free demo
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Philipp Thomaschewski
FRATCH CEO
