Jakarta Persistence (JPA) Experts in Cologne
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Meet FRATCH Experts in Cologne, who have recently used Jakarta Persistence (JPA)
Andreas B.
Last position:
Senior Software Developer at ELIONOVA AG
- Created an application to control measurement hardware with a Tauri application using React.JS and TypeScript on Raspberry Pi
- Developed a cloud application for storing and analyzing measurement results using Spring Boot and React.JS
- Built a Tauri application for printing ZPL labels on Windows
- Technologies: Java, JavaScript, Tauri, Rust, React.JS, AWS, Kubernetes, Docker, GitLab CI/CD, REST API (JSON), Maven, CI/CD, PostgreSQL
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.
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
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
Andreas E.
Last position:
Consultant at Iteratec GmbH
Kay O.
Last position:
Fullstack Developer at INIT GmbH
- Development of monitoring and control systems for public transportation
- Development of a platform for real-time monitoring of passenger information and ticketing systems, as well as an application for remote control and status monitoring of access control systems
- Development of dynamic forms, complex tables, real-time dashboards (SignalR), and reusable frontend components (using Storybook)
- Implementation of REST interfaces in the backend
- Deployment to the Microsoft Azure Cloud
- Technologies used: Angular 20, Angular Material 3, Dev Extreme, Storybook, C#/.NET 10
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
Jyothikrishna S.
Last position:
Senior Back-end Engineer at RLE Engineering and Services GmbH
- Works at Ford Motor Company as Senior Back-end Developer on contract via outsourcing
- Designed and developed REST APIs based on the analyzed requirements and technical standards
- Investigated issues and defects to determine root causes and formulate corrective action measures
- Participated in QA, stage, and production release activities
- Conducted code reviews for performance improvement
- Provided monitoring and support using GCP
- Used test driven and behaviour driven development approaches
- Took part in agile ceremonies
Jacqueline H.
Last position:
Kitchen Appliance Manufacturer
Setting up and enhancing an international subscription management system
Migrating and decommissioning a Hybris-SAP system and integrating Zuora
Implementing numerous interfaces to various systems (external and internal)
Setting up and improving monitoring with Grafana, Prometheus, and Databricks
Introducing logging with Loki
Implementing business requirements using jQuery, Thymeleaf, Spring Boot, Java, Go, and Python
Adjusting and extending the GitLab CI pipelines
Setting up and extending infrastructure as code with Terraform and ArgoCD on AWS
Setting up and running E2E and performance tests
Expanding the Databricks business intelligence solution to provide various KPIs
Responsibilities: Architecture, DevOps, development, unit tests, coaching employees and apprentices, E2E, smoke, and integration tests, agile methods consulting (Kanban, Scrum)
Technologies and methods: Java, Go, Kotlin, Node.js, Spring Boot, SOAP/REST, Quarkus, Thymeleaf, Vaadin, Slack, Jira, Confluence, IntelliJ, GitLab, SQS, Kafka, AWS, Kubernetes, Terraform, Maven, Gradle, GitLab CI, Databricks
Last position:
Rewe Digital
- Creation of Spring Boot integration tests
- Creation of JUnit tests for the coupon system
- Creation of component tests for Kafka topics
- Creation of CI/CD pipeline scripts
- Creation of UI tests with Playwright
- Creation of UI tests with Cypress
- Review of developer unit tests
- Planning the test architecture for integration tests
- Creation of the test automation concept
- Evaluation and creation of test reports
Jacqueline K.
Last position:
OTTO
- Design, development, and monitoring of microservices
- Migrating functions from a monolithic system into separate microservices
- Designing and implementing new microservices (backend and frontend)
- Setting up and maintaining a CI/CD pipeline (GitHub Actions)
- Configuring cloud infrastructure with AWS CDK and Terraform
- Designing and implementing event-driven communication with AWS SNS/SQS and Apache Kafka
- Ensuring code quality through Test Driven Development (TDD), static code analysis, and Clean Code
Discover over 15,000 top freelancers
Statistics of experts using Jakarta Persistence (JPA)
Aggregated from the professional profiles of matched freelancers.
Experience
20 years
Position duration
2.1 years
Positions per freelancer
11 (Germany: 14)
Top business areas
Information Technology, Product Development, Quality Assurance
Top industries
Information Technology, Retail, Automotive
Certification focus areas
Information Technology, Product Development, Marketing
Bachelor's degree or higher
100% (Germany: 96%)
Master's degree or higher
67% (Germany: 55%)
Doctorate
11%
Certifications per freelancer
2 (Germany: 3)
Most common languages
German, English, French
Speak two or more languages
100% (Germany: 96%)
Based on our profile pool as of 29 Oct 2026.
Daily rate distribution
The chart shows how the daily rates of experts in this technology in Cologne are distributed, based on recent contracts on our platform. Each bar covers a rate range — its height shows the share of experts charging within that range.
Average rates of experts in Cologne using Jakarta Persistence (JPA)
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 29 Oct 2026. Actual rates may vary depending on seniority level, experience, skill specialization, project complexity, and engagement length.
Jakarta Persistence (JPA) 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 (85%)
- Retail (62%)
- Automotive (54%)
- Banking and Finance (46%)
- Insurance (46%)
- Transportation (46%)
- Government and Administration (31%)
- Telecommunication (31%)
Please note that freelancers can work across multiple industries, so percentages overlap.
About the technology
Persistence foundation
Jakarta Persistence (JPA), formerly known as the Java Persistence API, is the standard for mapping Java objects to relational database records. It defines entity classes, relationships, queries and transaction behavior while leaving the database connection to an implementation such as Hibernate or EclipseLink. Teams use it to keep domain models and durable data aligned without writing every SQL operation by hand.
Application use cases
JPA appears in business applications that manage customers, orders, contracts, inventory and financial records. Strong entity design matters when data is shared across services, exposed through APIs or changed over many releases.
- Model entities, value objects and inheritance structures
- Map one-to-one, one-to-many and many-to-many relationships
- Build JPQL, Criteria API and native SQL queries
- Manage transactions, locking and fetch strategies
Ecosystem and tooling
JPA specialists commonly work with Hibernate ORM, EclipseLink, Jakarta EE, Spring Data JPA and relational databases such as PostgreSQL, MySQL or Oracle. Their surrounding toolkit may include Flyway or Liquibase for schema changes, Maven or Gradle for builds, and Testcontainers for realistic persistence tests. Understanding JDBC and SQL remains essential when abstraction hides an inefficient query.
When expertise matters
Companies bring in freelance specialists when a persistence layer is slow, difficult to change or producing inconsistent data. They help during migrations from older Java EE packages to Jakarta namespaces, database modernization, service extraction and major domain-model changes.
- Diagnose N+1 queries and unexpected lazy loading
- Review mappings, indexes and transaction boundaries
- Refactor fragile repositories without breaking behavior
- Prepare persistence code for cloud deployment and scaling
What strong specialists deliver
A capable JPA professional makes database behavior visible and testable. They choose loading strategies deliberately, keep transactions near clear business operations and inspect generated SQL instead of trusting defaults. They also document ownership, cascading, constraints and migration assumptions so future changes remain safe.
Collaboration in Cologne
Cologne companies can bring in local experts for workshops, architecture reviews or close collaboration with product and data teams. Remote delivery also works well when the project has clear database access, environments and documentation. German or English communication should match the team, while the technical handover should cover entity rules, queries, migrations and operational risks.
Frequently asked questions
The facts hiring teams ask for most often when it comes to Jakarta Persistence (JPA).
Jakarta Persistence (JPA) is used to map Java objects to relational database tables and manage their lifecycle within transactions. It supports entity relationships, JPQL queries, caching and optimistic locking, making it suitable for business applications with structured, durable data.
Jakarta Persistence (JPA) provides an object-relational mapping layer that reduces repetitive JDBC code and keeps domain models connected to persistence rules. Direct SQL or JDBC can offer tighter query control and simpler behavior for reporting or highly specialized workloads, so experienced specialists often combine both approaches.
Jakarta Persistence (JPA) is a specification, not a standalone implementation. Hibernate ORM and EclipseLink implement that specification, while Spring Data JPA adds repository patterns and convenience features on top of an implementation.
A strong Jakarta Persistence (JPA) specialist should also understand Java, SQL, relational modeling and transaction management. Experience with Hibernate, Spring or Jakarta EE, database migrations, testing and application observability is especially useful when persistence behavior affects production systems.
The right Jakarta Persistence (JPA) freelancer depends on the work rather than a fixed experience threshold. A focused mapping change may need strong knowledge of entities and tests, while a migration or performance investigation calls for proven judgment across SQL, transactions, schema evolution and production diagnostics.
Jakarta Persistence (JPA) work is well suited to remote collaboration when specialists can access representative databases, test environments and logs. Teams in Cologne should agree early on coding standards, review routines and whether workshops or key design sessions require on-site participation; communication can be in German or English.
Review whether Jakarta Persistence (JPA) code produces predictable SQL, clear transaction boundaries and tests for relationship and concurrency behavior. Ask the specialist to explain fetch plans, cascade choices, indexing assumptions and how they would detect N+1 queries or data inconsistency before accepting the implementation.
Bring in a Jakarta Persistence (JPA) specialist when slow queries, unclear mappings, failed migrations or transaction bugs threaten delivery. Freelance expertise is also valuable before a large domain-model change, a move from Java EE to Jakarta EE, or the separation of a monolith into services.
The average hourly rate of freelancers in Cologne, Germany who have used Jakarta Persistence (JPA) in their recent projects is 88 €, which corresponds to a daily rate of about 702 € based on an 8-hour working day.
Of the freelancers in Cologne, Germany who have used Jakarta Persistence (JPA) in their recent projects, 100% hold at least a Bachelor's degree, 67% hold at least a Master's degree, and 11% hold a doctorate.
On average, freelancers in Cologne, Germany who have used Jakarta Persistence (JPA) in their recent projects have 20 years of professional experience, with a single engagement typically lasting around 2.1 years.
The most common languages among freelancers in Cologne, Germany who have used Jakarta Persistence (JPA) in their recent projects are German (100%), English (100%), and French (31%).
The most common industries among freelancers in Cologne, Germany who have used Jakarta Persistence (JPA) in their recent projects are Information Technology (85%), Retail (62%), and Automotive (54%).
The most common business areas among freelancers in Cologne, Germany who have used Jakarta Persistence (JPA) in their recent projects are Information Technology (100%), Product Development (85%), and Quality Assurance (62%).
Main locations of FRATCH Experts, who have recently used Jakarta Persistence (JPA)
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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Hamburg 
Munich 
Frankfurt 
Stuttgart 
Dusseldorf Countries:
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