JSON Experts in Stuttgart
for reliable data exchange, matched with vetted freelancers in minutesHire experts who design clear data contracts, integrate REST and GraphQL APIs, and validate complex payloads across web, mobile and cloud systems. Get precisely matched with vetted, available freelancers who can support your JSON project quickly.
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
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
Ronald F.
Last position:
IT Consultant & Training at Various Small Projects & AI Training
- Development of multiple websites for small businesses (6)
- SEO/SEM
- Business Consulting (Implementation of ERP systems (Fresha / MS Dynamics))
- AI Tooling, Prompting & Coding
- GenAI Chatbot (GPT 4.0)
- Creation of a telephone agent (NLP services, Twilio, Python, Azure Services)
- Python coding, report & dashboard creation
- Stakeholder management and consulting throughout the project lifecycle
Training and Certifications in AI:
- Microsoft Azure AI Fundamentals
- Develop Gen AI Solutions with Azure Open AI Service
- Designing and Implementing a Microsoft Azure AI Solution
- Artificial Intelligence for the Business Professional
- Generative AI for the Business Professional
- Certified Artificial Intelligence Practitioner
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
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.
Elvir B.
Last position:
Software Architect and Software Developer at Noctica IT GmbH
- NocTime time tracking, workshop planner, meal delivery service app
- LLM-based chat bot to control the NocTime time tracking system via voice input
- New and further development of customer solutions based on the Noctica SAS app framework
- Technologies: Java 17, Spring Boot, JPA, Hibernate, JavaScript, TypeScript, Angular 20, Angular Material, React, C#, Docker, Bash, Git, GitLab, RedMine, SQL, DBeaver, MariaDB, PostgreSQL, Python, TensorFlow, Ollama, various LLMs
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 19 Sep 2026.
Daily rate distribution
The chart shows how the daily rates of freelancers in this technology in Stuttgart 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 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 19 Sep 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
What JSON is
JSON, short for JavaScript Object Notation, is a lightweight text format for representing structured data. Its objects, arrays, strings, numbers, booleans and null values are easy for systems to parse and people to read. JSON is widely used between browsers, applications, services and databases.
Where it is used
JSON sits at the centre of modern data exchange. Companies use it for API responses, configuration files, event payloads and document-oriented storage.
- REST and GraphQL API contracts
- Web and mobile application data
- Service-to-service messages
- Import, export and transformation pipelines
- Configuration for tools and cloud services
Ecosystem and tooling
Strong JSON work involves more than writing valid braces and key-value pairs. Specialists work with JSON Schema, OpenAPI, JSONPath and validation libraries, then connect payloads to JavaScript, TypeScript, Python, Java, .NET or other application stacks. They also use formatters, linters, contract tests and API documentation tools.
When companies need expertise
Freelance expertise is useful when data contracts are inconsistent, integrations keep breaking or a system is moving from a private interface to a public API. Stuttgart companies in automotive, manufacturing, logistics and software can also need support connecting older systems with cloud services and partner platforms.
- Define and document stable payload structures
- Find breaking changes between API versions
- Normalize data from different sources
- Improve validation, error handling and test coverage
What strong specialists deliver
Experienced professionals separate transport concerns from business rules and design payloads that remain understandable as systems evolve. They choose clear naming, consistent types, explicit optional fields and useful error responses. They understand encoding, escaping, date handling, numeric precision and security risks such as oversized or untrusted input.
Collaboration and results
A JSON specialist should be able to review an existing contract, explain trade-offs and leave behind practical documentation and tests. Remote collaboration works well when repositories, API specifications and example payloads are organized; on-site work in Stuttgart can help when interfaces cross factory, vehicle or operational systems. The result is predictable data exchange that is easier to integrate, monitor and maintain.
Frequently asked questions
Questions about JSON? Start with the answers below.
JSON is mainly used to exchange structured data between applications, especially through REST APIs and web services. It also appears in configuration files, event messages, data exports and document databases.
JSON is usually more compact and maps naturally to objects and arrays used in application code. XML offers richer document features and mature namespace handling, so the better choice depends on validation needs, legacy integrations and the systems already in place.
A strong JSON specialist should understand HTTP, REST, GraphQL, API versioning and authentication. Useful adjacent skills include JSON Schema, OpenAPI, database mapping, JavaScript or TypeScript, automated testing and observability.
JSON syntax is simple, but production work can involve complex contracts, legacy data and many consuming systems. Match the specialist to the integration risk: a focused transformation may need limited support, while a public API or migration calls for deep experience with validation, compatibility and testing.
JSON projects are often well suited to remote collaboration because specifications, examples, tests and API clients can be shared digitally. On-site sessions in Stuttgart can still help when the work connects factory equipment, vehicle systems or other operational environments.
Review whether the JSON contracts are consistent, documented and validated against realistic edge cases. Ask for examples of versioning, error responses, security controls and automated contract tests rather than judging quality from formatting alone.
JSON can represent deeply nested and complex structures, but nesting should remain purposeful and manageable. For very large payloads, high-throughput pipelines or strict binary efficiency, formats such as Protocol Buffers or Avro may be better suited.
A JSON assignment is rarely only about the data format. Clarify the API contract, source and target systems, encoding rules, validation expectations, compatibility requirements and the team’s working language; Stuttgart projects may also involve German-speaking stakeholders and on-site coordination.
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 835 € 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
