JSON Experts in Cologne
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Meet FRATCH Experts in Cologne, who have recently used JSON
Emre S.
Last position:
IT Project Manager | SAP E-Invoicing Outbound at Rohde & Schwarz
Project: Introduction of statutory-compliant electronic invoicing (outbound, Germany) in SAP for an international technology group.
- Project management: Planning, steering and reporting of the E-Invoicing outbound rollout across all affected business areas, including budget and resource coordination.
- UAT: Structured user acceptance test with key users per business area, test cases per invoice scenario, and consolidated test results for decision making.
- Defect management: Handover and tracking of defects in Jira, including validation of the generated invoices against the statutory schemas.
- Cutover, go-live and hypercare: Readiness checks and cutover planning aligned with the statutory deadlines, coordination of go-live and stabilization during hypercare.
- Stakeholder management and reporting: Alignment with Finance, Tax, business departments and IT, preparation of status reports and decision papers, and consistent follow-up of open items.
- Change management and documentation: Communicated process changes to the business departments, enabled key users, and created process and compliance documentation to ensure traceability and audit readiness.
Armen M.
Last position:
CTO/CPO Platform & Technology at Green Mobility Holding
- Overall responsibility for platform transformation across ERP, CRM, PIM and AI-supported process automation
- ERP transformation: Introduction and migration to Microsoft Dynamics 365 Business Central
- CRM & Growth Stack: Implementation of HubSpot as the central CRM and platform for lead and marketing automation
- Product data & Commerce Enablement: Introduction of an ePIM to scale Category Management and digital Commerce processes
- AI-supported process automation: Design and introduction of agent-based AI workflows to automate processes in Business Services, Accounting, Tender Management and Marketing
- Building a scalable platform organization consisting of Product Development, DevOps, UX, Cloud Engineering and Corporate IT
- Introduction of modern product and portfolio governance (e.g. OKRs, portfolio boards, value-based roadmaps) to manage technology-driven initiatives
- Harmonization of heterogeneous system landscapes and transformation into a modular, scalable platform architecture (ERP, CRM, PIM, integrated customer journeys)
- Coaching and development of Product Owners, Tech Leads, Delivery Managers and UX teams in building a scalable product organization
Henning U.
Last position:
Senior Expert Data Governance, Master Data Quality and Data Migration at E.ON
- Planning and implementation of a migration strategy for master and transaction data for the continuous loading of a cloud-independent database
- Creation and pilot implementation of a company-wide Business Data Model for customers, suppliers, contracts, products, prices, consumption, invoices, and dunning
- Concept and consulting for a Data Governance Framework incl. definition of committees, roles, processes, and metadata model
- Operationalization of the Data Governance Framework with definition of data standards
- Sub-project management in two pilot projects (PoCs) for Data Governance systems (ErwinDIS and Atlan)
- Training and coaching the data team in migration, data quality, and data modeling
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
Manuel S.
Last position:
Project Manager at Univention
Industry: digital sovereignty, public sector
Responsibilities:
- Project coordination (teams: consulting, development, testing, deployment/operations)
Products and standards:
- Jira, Confluence, Asana, Miro, Mural
- Open Source, Keycloak, Open Xchange, ownCloud
Muhammad J.
Last position:
Embedded Linux Intern – IoT Sensor Prototype Development at DHL
- Built a modular C++ 20 embedded Linux acquisition system on a Raspberry Pi, synchronizing IMU and dual-camera data streams to sub-millisecond accuracy.
- Integrated retro-reflective and contrast sensors to trigger acquisition and detect gaps between sorter rails.
- Implemented SPI & I2C sensor communication, GPIO interrupt handling with libgpiod, and CSV & JSON output.
- Designed a multi-threaded acquisition pipeline and an SPSC queue between acquisition and writer threads.
- Built a Python/HTML/CSS based web-server and validated the prototype in a DHL warehouse for defect detection.
- Documented software behavior, configuration, and results for maintainable handover and further development.
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
Stanislaus S.
Last position:
Security Consultant at Rohde & Schwarz AG at Star Labs GmbH
- Worked on FPGA enhanced network encryption device with secure boot, TPM2.0 and smart card integration for BSI approved usage with Post Quantum Cryptography
- Developed and audited Linux drivers
- Collaborated using GitLab, Gerrit, Confluence and Jira
- Technologies: C, C++, Secure Boot
Alexander R.
Last position:
Business Analyst at Financial Services Provider Landesbank
The Helaba ATLAS project aims to modernize core systems and make them future-proof. As part of the subproject, the existing legacy system for international payments is being replaced by a modern web-based application.
- Analysis of functional and technical requirements
- Analysis and optimization of business processes
- Process modeling
- Preparation and facilitation of workshops
- Defining project scope and prioritizing requirements
- Business process management (analysis, modeling, and optimization)
- Specification of user stories
- Designing business and authorization concepts
- Testing and acceptance
- Designing mockups in Figma
- Creating the UI/UX style guide for web applications Approach: Scrum (agile) Technologies: Jira, Confluence, MS Teams, Conceptboard, Java, Vaadin, Figma
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
Kai B.
Last position:
Freelance CPQ Consultant (Full-Time) at Freelance CPQ Consultant
- Independent CPQ consulting for a portfolio of industrial manufacturers, including Scheidt & Bachmann, Trützschler Group SE, and Weiss Klimatechnik GmbH (Schunk Group)
- Full project coverage: requirements analysis, concept, system design, implementation, testing, and international go-live support
- Deep integration work with SAP ECC (material master replication, SD document creation, material creation, general APICONNECT and other web service interfaces)
- Process consulting: analysis and optimization of internal quoting processes for sales and management
- Knowledge transfer/coaching and pair programming to strengthen internal team skills
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
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
Piet A.
Last position:
Frontend at Value Finance GmbH
- Developed a customer-facing application for a team of realtors to manage insurance and financial contracts
- Provided real-time insights into various insurance products, allowing realtors to manage, compare, and recommend contracts to clients
- Implemented a complex, reactive SVG visualization that displays key contract metrics for client presentations
- Worked with Nuxt 3, Tailwind, Google Firebase on the frontend and Node.js, MongoDB, PostgreSQL on the backend
- Followed Kanban, SCRUMBan, and Scrum methodologies
- Began learning Rust
Discover over 15,000 top freelancers
Statistics of experts using JSON
Aggregated from the professional profiles of matched freelancers.
Experience
20 years (Germany: 19 years)
Position duration
3.2 years (Germany: 5.2 years)
Positions per freelancer
13 (Germany: 14)
Top business areas
Information Technology, Product Development, Quality Assurance
Top industries
Information Technology, Banking and Finance, Insurance
Certification focus areas
Information Technology, Product Development, Project Management
Bachelor's degree or higher
90% (Germany: 89%)
Master's degree or higher
55% (Germany: 56%)
Doctorate
5% (Germany: 10%)
Certifications per freelancer
3 (Germany: 2)
Most common languages
German, English, French
Speak two or more languages
100% (Germany: 98%)
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 JSON
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.
JSON 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 (89%)
- Banking and Finance (56%)
- Insurance (44%)
- Retail (44%)
- Transportation (41%)
- Automotive (37%)
- Telecommunication (37%)
- Healthcare (30%)
Please note that freelancers can work across multiple industries, so percentages overlap.
About the technology
Data exchange format
JSON, short for JavaScript Object Notation, is a lightweight text format for structured data. Its objects, arrays, strings, numbers, booleans and null values are easy for software to parse and for people to inspect. It is a common contract between browsers, mobile apps, services and data tools.
Where JSON fits
JSON carries request and response data in REST APIs, GraphQL clients, configuration files, event messages and document stores. It supports product catalogues, customer records, content delivery, authentication flows and telemetry. Teams also use it to move data between services written in different programming languages.
- Define request and response schemas
- Map JSON to application models
- Connect web and mobile clients to APIs
- Import, export and transform records
Ecosystem and tooling
Strong JSON work includes JSON Schema for contracts and validation, JSON Pointer and JSON Patch for targeted changes, and JSON Lines for streaming records. Specialists often work with OpenAPI, HTTP, REST, GraphQL, jq, Postman and validators. They also understand serialization libraries in JavaScript, TypeScript, Java, Python, Go and .NET.
When expertise helps
Companies bring in freelance expertise when payloads have become inconsistent, integrations fail across teams or an API needs a stable contract. A specialist can review naming, nesting, data types, null handling, versioning and error responses before these choices spread through multiple systems. Cologne teams can combine on-site workshops with remote delivery when coordination requires it.
- Recover from breaking schema changes
- Improve API documentation and validation
- Convert legacy formats into JSON
- Reduce fragile client-side parsing
What strong specialists deliver
Experienced professionals treat JSON as part of a system contract, not just a text format. They define examples and edge cases, test malformed and unexpected input, and keep compatibility in mind when schemas evolve. They also distinguish transport concerns from business rules and protect sensitive fields during logging and transfer.
Choosing the right fit
Look for a portfolio that shows API contracts, schema validation and integrations rather than isolated JSON files. Ask how the professional handles backward compatibility, large payloads, optional fields, numeric precision and error reporting. For Cologne projects, clarify workshop language, working hours and the balance between local collaboration and remote execution before delivery begins.
Frequently asked questions
Curious about JSON? Here are the answers that come up again and again.
JSON is used to exchange structured data between applications, browsers, mobile clients and services. It also appears in API payloads, configuration files, event streams, document databases and data export workflows.
JSON is usually more compact and maps naturally to objects and arrays used in modern application code. XML offers richer document structure, attributes and mature namespace features, so the better choice depends on validation, interoperability and the surrounding system.
A capable JSON specialist should understand HTTP, REST, OpenAPI, JSON Schema and API testing. Knowledge of a programming language, databases, authentication, versioning and observability is also valuable because data format decisions affect the complete integration.
A JSON project may be small when it only needs a schema review or transformation script, but larger integrations require experience with contracts, compatibility and failure handling. Evaluate the scope by the number of systems, payload complexity, data sensitivity and consequences of breaking changes.
JSON work is well suited to remote collaboration because schemas, examples, test cases and API documentation can be reviewed online. Cologne teams may still prefer on-site workshops for complex contract decisions, while day-to-day implementation can remain remote with clear communication routines.
Review whether JSON schemas use consistent names, precise types, clear required fields and documented edge cases. Ask to see validation tests for malformed input, compatibility checks for changes and examples that reflect real production payloads.
JSON resembles JavaScript object syntax but follows stricter rules: property names use double quotes, and it does not support functions, comments or undefined values. A JavaScript object may contain language-specific values that cannot be serialized as valid JSON.
A JSON professional may deliver schemas, API examples, validation rules, transformation logic, test collections and migration scripts. The engagement can also include documentation, compatibility guidance and a review of how payloads are logged, secured and monitored.
The average hourly rate of freelancers in Cologne, Germany who have used JSON in their recent projects is 100 €, which corresponds to a daily rate of about 797 € based on an 8-hour working day.
Of the freelancers in Cologne, Germany who have used JSON in their recent projects, 90% hold at least a Bachelor's degree, 55% hold at least a Master's degree, and 5% hold a doctorate.
On average, freelancers in Cologne, Germany who have used JSON in their recent projects have 20 years of professional experience, with a single engagement typically lasting around 3.2 years.
The most common languages among freelancers in Cologne, Germany who have used JSON in their recent projects are German (100%), English (100%), and French (22%).
The most common industries among freelancers in Cologne, Germany who have used JSON in their recent projects are Information Technology (89%), Banking and Finance (56%), and Insurance (44%).
The most common business areas among freelancers in Cologne, Germany who have used JSON in their recent projects are Information Technology (100%), Product Development (89%), and Quality Assurance (63%).
Main locations of FRATCH Experts, who have recently used JSON
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 
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Stuttgart 
Dusseldorf 
Dortmund 
Essen 
Nuremberg Request a free demo
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FRATCH CEO
