JSON Experts in Stuttgart
for reliable data exchange, matched in minutes with vetted freelancersHire experts who design clear JSON schemas, integrate REST APIs and validate complex data flows across web and mobile systems. FRATCH matches you quickly and precisely with vetted, available freelancers who fit your technical needs.
Meet FRATCH Experts in Stuttgart, who have recently used JSON
Karin A.
Last position:
AI Benchmark Engineer | Native language specialist German at Lilt
- Task Engineering: Evaluating Coding Agents.
- Asset Creation: Building realistic task environments using datasets and files in German. Crucially, these assets must remain in the target language to genuinely measure multilingual handling.
- Prompting & Translation: finding failure points where AI does not work, in German.
- Implementation & Verification: Supporting the development of robust solutions (reference implementations) and write highly reliable, deterministic verifier scripts (using rubric-based judging only when strictly necessary).
- Calibration & Execution: Analyze execution logs and calibrate task difficulty (Easy to Very Hard) using standard Terminal-Bench run configurations against various model tiers (Haiku, Opus).
- Quality Assurance: Participation in a rigorous, 4-layer human quality control process (creation, human review, calibration review, and audit) alongside automated LLM-based checks to ensure fairness, grammatical accuracy, and benchmark integrity.
- Linguistic Review: Reviewing AI benchmark tasks across Hindi, Arabic, Japanese, Chinese, Czech and Turkish.
Matthias S.
Last position:
Software Developer and Consultant at CLADE GmbH
- Analysis of the existing CAN communication between microcontrollers
- Analysis of the sensors used and the measured values collected
- Planning the CAN messages for transmitting the measured values
- Iterative adjustment of the microcontroller code to the new CAN messages
- Cross-compilation from x64 to arm64
Ronald F.
Last position:
Senior IT Consultant – Requirement Engineer at Deutsche Bank - Strivion
Methodology: Agile project management
Goal: Digitization and implementation of CCD2 requirements within the Consumer Finance systems.
Analysis, identification, and assessment of business requirements, as well as their transfer into technical implementation requirements. Coordination and status reporting of the various requirements. Documentation and process management using UML and BMPN. Cross-functional stakeholder management, UAT testing, data management, API architecture management.
Tools: Jira, Confluence, Visual Code, Sql Developer, Enterprise Architect, MsOffice, Bruno, ALM, Camunda, Figma
Alexander Z.
Last position:
Fullstack Developer and DevOps Engineer at Freelancer
- Developing the infrastructure and improving existing infrastructure: Jenkins, Gitlab Pipeline, OpenShift, Docker, Helm Chart, Kubernetes, Artifactory, CodePipeline, CodeArtifact, Python
- Documenting solutions in Jira/Confluence
- Supporting other colleagues in different technical areas
German R.
Last position:
Freelance Technical Product Owner & AI Product Builder at Neckarshore AI / Freelance
Two complementary tracks: (a) building my own AI products and open-source tools under the Neckarshore AI brand, with a focus on AI-supported multi-agent development processes and documentation automation; (b) freelance support for industrial, logistics, and financial companies in IT-related transformation projects.
Current product portfolio under the Neckarshore AI brand:
- Omnopsis Documenter — AI-powered documentation engine: generates compliance, technical, and release documentation from Git, Jira, and Confluence. 500+ automated tests, 100+ API endpoints, RBAC, monitoring stack.
- TrustScope — trust analysis for public GitHub repos: deterministic three-pillar report (Security & Supply Chain, Governance, Community) based on OpenSSF Scorecard, with constructive fix suggestions instead of a single misleading score.
- md-viewer — dependency-free Markdown viewer for macOS (Finder Quick Action) and web, split view of rendered document and raw text.
- Obsidian Vault Autopilot — AI-supported vault automation for Obsidian × Claude Code: sorts the inbox, renames notes, enriches frontmatter.
- Phonesis Voice Bank — voice archive for families, hospices, and cultural archives (guided recordings, inheritable archive, optional voice cloning); currently in the GDPR compliance phase (Art. 9, biometric data).
- Multi-Agent Development Process — 12+ specialized agents (architecture, implementation, security, refactoring, marketing) with structured handoff protocol, parallel execution, and automated quality assurance — powers the entire product development.
- Freelance consulting: Technical Product Ownership for production, logistics, and compliance/AML systems; steering international rollouts including test, cutover, and change management.
Stack: NestJS, TypeScript, PostgreSQL, Redis/BullMQ, Next.js, Claude Code (Opus), Docker, GitHub Actions, Vercel
Gildas D.
Last position:
System Team Lead Diagnostics – Hybrid & Electric Drives (HEV/MHEV/PHEV) for Transmission and Engine (NA/SA) at Stellantis e-transmission
- Technical lead of diagnostics activities for eDCT transmissions and drive systems in the area of hybrid (HEV), mild-hybrid (MHEV), and plug-in hybrid vehicles (PHEV)
- Responsibility for the development and validation of DTC strategies (OBD / EOBD) for markets in North and South America and the EU
- Coordination between interdisciplinary teams (system development, software, safety, calibration, after-sales)
- Creation and maintenance of diagnostic specifications (DID, DTC matrix, snapshot, freeze frame) according to STLA standards
- Support with troubleshooting, validation tests, EOL processes, and internal audits
- Technical interface to suppliers (Bosch, Valeo, etc.) in the area of actuators, sensors, and electric pumps
- Creation of diagnostic RFQ
Robin S.
Last position:
Senior Cloud & Backend Engineer at Media-Saturn-Holding GmbH
- Implementing applications with Kotlin and Ktor as microservices
- Using MongoDB in the MongoDB Atlas cloud
- Asynchronous communication of services via Google Pub/Sub
- Using Kotest and MockK for unit tests
- Developing an administration frontend with TypeScript, React and Express.js
- Provisioning environments in GCP using Terraform
- Implementing CI/CD processes with GitHub Actions
- Operating scalable production and test environments in GCP with Kubernetes, Helm and Flux CD
- Monitoring environments with Prometheus and Grafana
- Providing BI data in the Google BigQuery data warehouse
Benjamin S.
Last position:
Design and implementation of a new cloud service at Porsche AG
- Design of a new cloud service
- Requirements Engineering
- API Design (REST API, Kafka)
- Consulting on architecture, feasibility and effort estimation
- Implementation of a microservice architecture
- Implementation of a Spring Boot web service
- Development of REST APIs including business and persistence logic
- Kafka consumers and producers
- Various Excel upload/download scenarios
- Change Data Capture
- Cloud provisioning with IaC/Terraform
- Go-live with 30,000 users
- Operation, support and bug fixing for other services
Environment/tools: GitLab, JIRA, Confluence, IntelliJ, Spring Boot, Java, Docker, Terraform, AWS ECS, Postgres, Apache Kafka, SAP Datasphere, JUnit, Debezium, Apache POI, Hibernate, JPA, Testcontainers
Achille C.
Last position:
Backend/Frontend Developer at ITZ-Bund
Development of a microservice application for calculating postings on accounts
Development of backend components with Java or JEE, Quarkus, Kafka, Rest API
Development of the test component with mocking frameworks (Mockito)
Development of integration test components
Creation of OpenAPI specification format
Configuration of CI/CD pipeline
Development of frontend components with React
Design, further development and optimization of system structures
Code review
Java Corretto 21, JEE, Quarkus, Golang
Reactive programming with Spring WebFlux, Project Reactor
Git, Azure DevOps for CI/CD pipeline, YAML, Json Swagger UI, Postman, Rest OpenAPI, Kafka Streams, Kafka Connect, Log4J
Microservices, Jira, Confluence, MySQL, Docker, Kubernetes (deployment via Helm charts)
Spring Security, OAuth 2, JWT, Sonarqube
IntelliJ, Maven, logging framework Splunk, Agile method Scrum, Nexus, Vaadin V24, build tool Vite
React, React.JS, Node.js, Jess/JavaScript, Tailwind CSS, Agile method Scrum, accessibility BITV, Playwright
Mangal M.
Last position:
Trainee Product Management at Digitale Leute Schule
- Remote learning with experts and 636 instructional units.
- Product management bootcamp teaching agile methods and software tools for modern product management in complex software projects.
- User experience (UX) · product management · Figma (software) · user-centered design · Scrum · agile project management · Jira · Confluence · product discovery · backlog management · user experience design (UED) · prototyping · lean thinking · product roadmapping · user stories · Miro collaboration platform · application monitoring tools · performance metrics · lean product management · product design kickoff indicators (KPI) & tracking events · product strategy · business modeling · product vision & goals · product discovery.
Alban T.
Last position:
C/C++ Developer on AIX Systems for SAP Kernel System Integration at IBM Research and Development
- AIX/Linux system administrator: deployment of LPARs (Logical Partitions) for SAP Kernel Development
- C/C++ SAP kernel development and integration to SAP HANA Database
- C/C++ programming and software integration, support for SAP kernel on AIX system; development and testing on SAP VDI
- Example: development of the ABEC Tool (AIX Build Environment Checker) to create SAP build environments for debugging process and benchmarking
- Benchmarking and test execution of SAP kernels (test from the communication to the SAP HANA Database and to SAP NetWeaver) on AIX
- Automate the SAP kernel build via Jenkins and benchmarking over crontab jobs
- New C/C++ compiler design and testing (based on Clang++ and LLVM)
- Customer ticket handling to resolve SAP kernel bugs and build failures
- SAP kernel development with Rust programming language, migrating some sub-kernel projects from C/C++ to Rust because of Rust's memory safety model, ownership system, and concurrency features
- Refactoring selected components in Rust and integrating them with existing C++ codebase via FFI
Gerhard W.
Last position:
Self-employed Software Developer at Self-employed Software Developer
- OpenStreetMap integration for a logistics system of PTV Transport GmbH
- Contributed to portal software
- Webshop system in PHP with login, shopping cart, order management and PDF invoice module, AdminLTE
- Cash book application for managing income and expenses (including export functions)
- Helpdesk system with ticket management, user roles and automatic notifications
Michael B.
Last position:
Developer/Consultant at Fresenius Medical Care
- Development of automated end-of-line tests (functional tests) for dialysis machines on a PLC test bench in a production environment
- Introduction of new technology based on Vector vTestStudio, CANoe, and Siemens S7 PLC
- Creating test concepts
- Implementing test cases and libraries in CAPL and C#
- Touch screen emulation and proprietary RPC (Remote Procedure Call) via CAN
- Connecting to the PLC (Siemens Simatic)
- Defining interfaces for device communication (vCDL)
- Defining user interfaces and linking to the frontend (JSON)
- Agile work using DevOps (Azure)
- Skills: CAPL, .NET, C#, vCDL, CANOpen, DevOps, PLC
- Tools used: Vector CANoe 18, vTestStudio 4, MS Azure DevOps, MS Visual Studio 2022, Mosquito MQTT, Git, Siemens TIA Portal
Harald B.
Last position:
Software Architect at Amoria Bond
- Developed gateway demonstrator
- Defined system requirements for topology and data concentrator
- Designed zonal controllers for Leoni
Erol T.
Last position:
Continental AG
- Analyze and fix data flows between PMD and SAP HR/S4 systems using SAP PI/PO and ABAP, especially in the HR area.
- Provide integration services by developing, customizing, and troubleshooting issues in custom interfaces and processes.
- Participate in technical and functional discussions to align the HR system architecture and integration strategies.
- Ensure system stability and data accuracy by proactively identifying and resolving integration issues to contribute to ongoing project success.
- Transfer HR data via OData service to SuccessFactors ABAP-OO report: access LDAP user data alongside SAP user data and update the email address and Windows ID in SAP.
- S/4 HANA, ABAP/4, ABAP-Object, S/4 HR, FI, SoapUI, Postman, REST API, JSON.
Discover over 15,000 top freelancers
Statistics of experts using JSON
Aggregated from the professional profiles of matched freelancers.
Experience
22 years (Germany: 19 years)
Position duration
2.1 years (Germany: 5.2 years)
Positions per freelancer
16 (Germany: 14)
Top business areas
Information Technology, Product Development, Quality Assurance
Top industries
Information Technology, Automotive, Manufacturing
Certification focus areas
Information Technology, Product Development, Project Management
Bachelor's degree or higher
100% (Germany: 89%)
Master's degree or higher
50% (Germany: 56%)
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 Stuttgart 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 Stuttgart 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 (88%)
- Automotive (71%)
- Manufacturing (65%)
- Banking and Finance (53%)
- Healthcare (35%)
- Professional Services (35%)
- Government and Administration (35%)
- Aerospace and Defense (29%)
Please note that freelancers can work across multiple industries, so percentages overlap.
About the technology
Data format
JSON, short for JavaScript Object Notation, is a lightweight text format for structuring and exchanging data. Its objects, arrays, strings, numbers and Boolean values are easy for systems to parse and for people to read. Companies use it as a common language between browsers, mobile apps, backend services and external APIs.
Typical uses
JSON appears across modern software delivery, from a small web form to distributed business systems. Specialists use it to define payloads, configuration files and stored documents.
- Connect REST APIs with web and mobile applications
- Model customer, product and transaction data
- Configure tools, services and deployment workflows
- Transform data between applications and databases
Ecosystem and tooling
Strong JSON work involves more than writing correctly shaped text. Professionals work with JSON Schema, OpenAPI, REST, GraphQL responses and tools such as jq, Postman and language-specific serializers. They also understand HTTP methods, status codes, authentication, versioning and the differences between JSON documents and JSON Lines used for streamed records.
When to bring in expertise
Freelance specialists are useful when an API contract is unclear, integrations fail at field boundaries or a migration must preserve existing data. They can establish naming conventions, validation rules and compatibility policies before several teams build against the same interface. For companies in Stuttgart, this can support connected manufacturing, mobility, software and service operations while keeping collaboration remote or on site.
- Review inconsistent payloads and undocumented endpoints
- Create schemas and contract tests for an API
- Plan changes without breaking consuming applications
Quality signals
A capable professional treats JSON as part of a dependable interface, not as an arbitrary collection of fields. They use explicit schemas, meaningful error responses, predictable optional values and suitable data types. They consider security as well: sensitive fields should be limited, inputs validated and deeply nested or oversized payloads handled safely.
They can explain trade-offs between compactness, readability and backward compatibility. They also test malformed input, null handling, character encoding and serialization behavior in the languages used by the surrounding system.
Working together
A project rarely needs JSON knowledge in isolation. Look for adjacent experience with API design, backend or frontend integration, databases, automated testing, documentation and observability. Ask a specialist to walk through a real contract, explain how changes are versioned and show how validation is enforced in delivery pipelines.
Remote collaboration works well when schemas, examples and decisions are documented clearly. In Stuttgart, on-site workshops may help when JSON interfaces connect software with physical operations, but the core work can remain distributed. Clear technical English is usually sufficient; German may help when requirements involve local stakeholders.
Frequently asked questions
Questions about JSON? Start with the answers below.
JSON is used to exchange structured data between applications, browsers, services and tools. It commonly carries REST API requests and responses, stores configuration, and represents records during imports or exports.
JSON is usually more compact and maps naturally to objects and arrays used in many programming languages. XML offers richer document features, namespaces and attribute support, so the right choice depends on validation, document structure and the systems that must consume the data.
JSON work is strongest alongside REST API design, HTTP, JSON Schema, OpenAPI and automated contract testing. Useful specialists also understand databases, serialization libraries, authentication, versioning and the application language on both sides of an integration.
JSON itself is easy to read, but reliable integration work requires judgment about contracts, validation, errors and compatibility. A small transformation may need focused support, while a shared API or migration calls for a specialist who has handled production interfaces and changing data models.
JSON projects are well suited to remote collaboration because schemas, examples, tests and API documentation can be reviewed online. On-site sessions in Stuttgart can still be valuable when teams are aligning software interfaces with manufacturing, mobility or other operational systems.
JSON Schema describes the expected structure, types, required fields and constraints of a JSON document. It helps teams validate payloads, generate documentation and detect breaking changes before data reaches connected applications.
JSON normally describes one complete document, while JSON Lines stores separate valid JSON values on individual lines. JSON Lines is useful for logs, streaming and large data processing because records can be read incrementally.
Ask a JSON specialist to explain a real API contract, including validation, error handling, optional fields and compatibility rules. Strong professionals use clear examples and tests, identify security risks, and connect data decisions to the needs of the consuming systems.
The average hourly rate of freelancers in Stuttgart, Germany who have used JSON in their recent projects is 104 €, which corresponds to a daily rate of about 834 € based on an 8-hour working day.
Of the freelancers in Stuttgart, Germany who have used JSON in their recent projects, 100% hold at least a Bachelor's degree and 50% hold at least a Master's degree.
On average, freelancers in Stuttgart, Germany who have used JSON in their recent projects have 22 years of professional experience, with a single engagement typically lasting around 2.1 years.
The most common languages among freelancers in Stuttgart, Germany who have used JSON in their recent projects are German (100%), English (100%), and French (47%).
The most common industries among freelancers in Stuttgart, Germany who have used JSON in their recent projects are Information Technology (88%), Automotive (71%), and Manufacturing (65%).
The most common business areas among freelancers in Stuttgart, Germany who have used JSON in their recent projects are Information Technology (100%), Product Development (94%), and Quality Assurance (82%).
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.
Berlin 
Hamburg 
Munich 
Cologne 
Frankfurt 
Dusseldorf 
Dortmund 
Essen 
Nuremberg Request a free demo
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FRATCH CEO
