Jakarta Persistence (JPA) Experts in Cologne
, matched with vetted freelancers in minutesHire experts who design persistence layers, map Java domain models to relational databases and optimize transaction-heavy applications with Jakarta Persistence (JPA), Hibernate and Spring Data JPA. FRATCH connects you with precisely matched, vetted and available freelancers quickly.
Meet FRATCH Experts in Cologne, who have recently used Jakarta Persistence (JPA)
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
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
Andreas B.
Last position:
Senior Frontend Developer at Roadex
- Development of an app
- Technologies: React Native, Expo, SupaBase, TypeScript, GitHub, Trello
Kay O.
Last position:
Fullstack Developer at INIT GmbH
- Development of monitoring and control systems for public transport
- Development of a platform for real-time monitoring of passenger information and ticketing systems and an application for remote control and status monitoring of access systems
- Development of dynamic forms, complex tables, real-time dashboards (SignalR), and reusable components in the frontend (using Storybook)
- Implementation of REST interfaces in the backend
- Deployment to Microsoft Azure Cloud
- Technologies used: Angular 20, Angular Material 3, Dev Extreme, Storybook, C#/.NET 10
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
Sara S.
Last position:
Senior Software Developer with a Focus on UI/UX at vGen GmbH
Development of an interactive prototype for the concept of an AI-supported Enterprise Architecture Management tool. The goal was to present complex relationships between IT systems, business processes, and departments in a way that is easy to understand and to support decision-making in the context of IT transformations.
The prototype combined data-driven analyses with guided questions and interactive visualizations. A central part was the integration of a RAG process to provide domain-specific EAM knowledge in context. The focus was on quick idea validation, user-centered interaction design, and the technical feasibility of a scalable overall concept.
Design, implementation, and validation of a RAG process for domain-specific EAM knowledge with Python, LangChain, and graph/vector databases (Neo4J, Milvus)
Business and technical requirements analysis as well as definition of an MVP
Development of the architecture and technology concept using Angular, Spring Boot, GraphQL, and Kubernetes
Design of an interaction concept and creation of a brand style guide with Figma
Development of interactive prototypes with Angular, Konva.js, and TypeScript
Integration of CI/CD processes with GitLab CI/CD
Discover over 15,000 top freelancers
Statistics of experts using Jakarta Persistence (JPA)
Aggregated from the professional profiles of matched freelancers.
Experience
18 years (Germany: 20 years)
Position duration
1.9 years (Germany: 2 years)
Positions per freelancer
10 (Germany: 13)
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
70% (Germany: 55%)
Doctorate
10%
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 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 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 19 Sep 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 (86%)
- Retail (57%)
- Automotive (50%)
- Banking and Finance (43%)
- Insurance (43%)
- Transportation (43%)
- Telecommunication (36%)
- Government and Administration (29%)
Please note that freelancers can work across multiple industries, so percentages overlap.
About the technology
Persistence for Java
Jakarta Persistence (JPA) is the standard Java API for mapping objects to relational database tables. It defines entities, relationships, queries, transactions and lifecycle rules, while implementations such as Hibernate provide the runtime behavior. The technology was formerly known as Java Persistence API and remains widely called JPA.
What It Builds
JPA supports the data layer of business applications that need durable, structured information and consistent transactions. It appears in customer portals, commerce systems, finance software, inventory tools and enterprise services built with Jakarta EE or Spring.
- Model entities and relationships
- Persist aggregates across transactions
- Query data with JPQL, Criteria API or native SQL
- Handle lazy loading, cascading and locking
Ecosystem and Tooling
Strong specialists understand the boundary between the JPA specification and its implementation. Common tools include Hibernate ORM, EclipseLink, Spring Data JPA, Jakarta EE, Spring Boot, Maven or Gradle, and relational databases such as PostgreSQL, MySQL and Oracle. They also work with schema migration tools, connection pools and observability libraries.
When to Bring in Expertise
Companies often need freelance expertise when an existing persistence layer is slow, difficult to change or producing inconsistent data. A specialist can support a new service, modernize Java EE applications, replace direct JDBC usage or prepare a migration from javax.persistence to jakarta.persistence. Cologne teams may also value professionals who can combine remote delivery with effective on-site workshops.
Delivery and Quality
A capable professional starts with the domain model, access patterns and transaction boundaries rather than generating entities mechanically. They define clear repository boundaries, review generated SQL, select fetching strategies carefully and protect APIs from accidental persistence concerns. Automated integration tests with a real database are essential for validating mappings and transaction behavior.
Skills Around JPA
JPA work connects application design with database engineering. Useful adjacent skills include Java, Spring Boot or Jakarta EE, Hibernate internals, SQL tuning, REST APIs, messaging, testing, Docker and CI pipelines. The best fit can explain trade-offs clearly, document migration risks and collaborate in the language and working style required by a Cologne-based team.
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 records and manage their lifecycle. It helps applications handle relationships, queries, transactions, caching and concurrency without placing SQL in every business operation.
Jakarta Persistence (JPA) provides an object-relational mapping model, while JDBC gives direct control over SQL, connections and result sets. JPA can reduce repetitive data-access code, but JDBC or a query-focused tool may be preferable for highly specialized SQL and reporting workloads.
Jakarta Persistence (JPA) is a specification, not a complete implementation. Hibernate ORM and EclipseLink implement that specification, so a project can use JPA concepts while relying on Hibernate-specific capabilities where they are justified.
Jakarta Persistence (JPA) work benefits from strong Java, SQL and relational database knowledge. Experience with Hibernate, Spring Data JPA, Spring Boot or Jakarta EE, transaction design, schema migrations and integration testing is also valuable.
Jakarta Persistence (JPA) projects vary from straightforward entity mapping to complex systems with inheritance, locking, batch processing and large data volumes. Choose a professional based on the project’s transaction model, database risks and migration scope rather than on the technology label alone.
Jakarta Persistence (JPA) work is well suited to remote collaboration because mappings, queries, tests and database behavior can be reviewed through shared repositories and development environments. For teams in Cologne, occasional on-site architecture sessions can complement remote implementation, with German or English agreed in advance.
Jakarta Persistence (JPA) applications often suffer from unintended eager loading, N+1 queries, oversized persistence contexts or inefficient pagination. A strong professional inspects generated SQL, measures query behavior, chooses fetch plans deliberately and tests with realistic data access patterns.
Jakarta Persistence (JPA) quality is visible in clear entity boundaries, explicit transaction ownership, predictable queries and tests against the target database. Ask the specialist to explain cascade settings, fetch choices, locking, migration handling and how production issues would be diagnosed.
The average hourly rate of freelancers in Cologne, Germany who have used Jakarta Persistence (JPA) in their recent projects is 89 €, which corresponds to a daily rate of about 712 € 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, 70% hold at least a Master's degree, and 10% hold a doctorate.
On average, freelancers in Cologne, Germany who have used Jakarta Persistence (JPA) in their recent projects have 18 years of professional experience, with a single engagement typically lasting around 1.9 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 (29%).
The most common industries among freelancers in Cologne, Germany who have used Jakarta Persistence (JPA) in their recent projects are Information Technology (86%), Retail (57%), and Automotive (50%).
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 (86%), and Quality Assurance (64%).
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.
Berlin Hamburg Munich 
Cologne Frankfurt Stuttgart Dusseldorf Leipzig Dortmund Essen Bremen Dresden Hanover Nuremberg 
Berlin 
Hamburg 
Munich 
Frankfurt 
Dusseldorf Countries:
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