AssertJ Experts in Germany
in minutes with vetted, available specialistsHire experts who write clear fluent assertions, improve test readability, and build reliable JUnit test suites with AssertJ, AssertJ Core, and related Java testing tools. Get fast, precise matching with vetted, available freelancers.
Meet FRATCH Experts in Germany, who have recently used AssertJ
Fred Hauschel
Last position:
Software Architect and Developer at Personal project
A recurring problem in my own AI-supported projects: requirements analysis, use cases, and architecture decisions can be created quickly with AI support, but they remain hard to trace 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 as a continuously linked knowledge graph, traceable from the requirement to the architecture decision – queryable for both people and AI agents alike. Technically based on RDF/OWL and its own MCP server.
Result: MCP daemon running, Docker image automatically published on GHCR, nine hexagonal modules, eleven ADRs (including an open-core licensing model). Requirements engineering and ubiquitous language hexagon active. Publicly available since 07/2026 as a Community Edition under Apache-2.0 (github.com/kogn-io/arknet), together with the Claude Code plugin and the 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
Tymofii Sukhachov
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.
Jens Oberender
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
Marcus Biel
Last position:
Java Cloud Expert at Unknown
- Modernized and modularized a legacy monolith to enable independent team workflows
- Migrated from Java 8 to Java 21 and from Spring Boot 2 to Spring Boot 3.3
- Simplified Maven project structure, reducing build time from 15 minutes to 50 seconds
- Converting architecture to a hexagonal DDD architecture with end-to-end integration tests using RestAssured and JUnit 5
- Tools and technologies: Java 8-22, Spring Boot, Mockito, AssertJ, RestAssured, Hibernate, OracleDB, Flyway, REST, JSON, Docker, Kubernetes, AWS, Bitbucket, GitHub, SonarQube, IntelliJ IDEA Ultimate
Celil Uzunel
Last position:
ZÜRS Geo 2021 at adesso SE
- Frontend development
- Spring Boot
- Swagger
- Git
- GitLab
- SonarQube
- Docker
- Maven
- Java
- Angular
Michael Fecher
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 Bolte
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 Simon
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 Bieniek
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
Orhan Keskin
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
Adil Sultan
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
Johannes Erchen
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 Bocsak
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 Dobre
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 Mönnich
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, Product Development, Project Management
Bachelor's degree or higher
92%
Master's degree or higher
83%
Doctorate
25%
Certifications per freelancer
2
Most common languages
German, English, Spanish
Speak two or more languages
100%
Based on our profile pool as of 30 Aug 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 30 Aug 2026. Actual rates may vary depending on seniority level, experience, skill specialization, project complexity, and engagement length.
About the technology
What it does
AssertJ is a Java assertion library used to make tests easier to read and easier to maintain. It replaces long, brittle checks with fluent assertions that describe intent clearly. Teams use it in unit tests, integration tests, and API checks.
Where it fits
- JUnit test suites that need clearer failure messages
- Spring and Spring Boot services with many business rules
- API, JSON, and collection assertions in backend tests
- Legacy test code that needs cleaner, more expressive checks
It fits well when teams want test code that reads like a sentence instead of a chain of low-level comparisons.
Ecosystem
AssertJ is often used with JUnit, Mockito, Maven, Gradle, Spring Boot, and Hamcrest migrations. Strong specialists know the core API, custom assertions, soft assertions, and how to extend the library for domain objects. They also know when a plain assertion is better than a clever one.
Why companies bring in specialists
Companies look for AssertJ specialists when tests are hard to read, failures are hard to debug, or old assertion styles slow down delivery. In Germany, this often comes up in teams modernizing Java backends, service layers, and internal platforms. Freelance help is useful for test refactoring, review work, and setting up shared patterns across squads.
What strong work looks like
A strong professional writes assertions that are specific, stable, and easy to understand. They use the right level of fluency without hiding the intent of the test. Good specialists also keep the focus on behavior, not on implementation detail.
Common project tasks
- Refactor existing test suites from verbose assertions to AssertJ
- Create reusable custom assertions for domain models
- Improve failure output for faster debugging
- Coach teams on AssertJ usage and test style
The best experts leave behind test code that other specialists can extend without friction.
Frequently asked questions
Questions about AssertJ? Start with the answers below.
AssertJ is used to write fluent, readable assertions in Java tests. It helps teams check objects, collections, strings, exceptions, and API responses with clearer intent than many older assertion styles. That makes failures easier to understand and tests easier to keep up to date.
AssertJ usually reads more naturally than basic JUnit assertions and is often more expressive than Hamcrest matchers. Teams choose it when they want cleaner test code and better failure messages. It is also a common choice when replacing older assertion styles in existing Java suites.
A strong AssertJ specialist usually knows JUnit, Mockito, and the surrounding Java test stack. They should also understand test design, fluent APIs, and how to build custom assertions for domain objects. In Spring Boot projects, they often need to work well with service tests and integration tests too.
AssertJ help becomes valuable when test code is verbose, inconsistent, or hard to trust. It is also useful during refactoring, when teams want to standardize assertion style across a codebase. If failures are slow to diagnose, a specialist can usually improve that quickly.
Yes. AssertJ work is usually easy to do remotely because it centers on code review, test refactoring, and pair programming. For teams in Germany, remote collaboration works well when English is the shared working language, while on-site sessions can help during larger cleanup efforts or team coaching.
AssertJ is especially useful in unit tests, service tests, and integration tests that check rich Java objects. It also works well for JSON payloads, collections, optional values, and exception handling. Teams often notice the biggest gain where assertions have become long and repetitive.
Look for clear, focused test examples rather than clever one-liners. A strong AssertJ professional writes assertions that explain behavior, uses custom assertions where they add value, and avoids overcomplicating simple checks. Good failure messages and consistent style are strong signs of quality.
AssertJ is often very effective in legacy suites because it makes tests easier to read during cleanup. Specialists can convert fragile assertion blocks step by step without rewriting the whole suite at once. That makes it a practical choice for gradual modernization.
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, 83% hold at least a Master's degree, and 25% 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
