Expert for fullstack development with React, TypeScript, Node.js, Java, Scala - Martin Siegling | Freelancer

Consulting & Development

As an independent IT consultant and freelancer with a focus on React and TypeScript - and many years of experience in Java and Scala as well - I support companies in building modern, scalable software solutions. I also offer specialized expertise in AI chatbots and GDPR-compliant solutions. My key areas of focus include:

Fullstack web development with React, TypeScript,Node.js and various databases, based on a fully decoupled frontend/backend architecture
Architecture consulting and technical leadership for organizations
AI integration (OpenAI, Azure OpenAI, DeepSeek, chatbots, NLP)
Implementation of GDPR-compliant consent management systems

I work as a remote freelancer and fullstack developer for companies across Germany and Europe, offering:

Technical leadership for software projects based on React, TypeScript, Node.js and Java
Design and development of web analytics solutions (especially server-side tracking)
Development of custom chatbot solutions connected to OpenAI or other providers
Remote engagements across Germany and Europe – project-based or day-based
20+ years of project experience with banks, media, industry and IT

Recent Projects

Design and implementation of a web based tool for financial planning and forecasting (2025)

Role: Fullstack Engineer including one-stop architecture, backend design and UI components as well as data modelling and backend structure with Prisma/PostgreSQL, separated by TRPC

TypeScript, React, tailwindcss, Prisma, PostgreSQL, TRPC, Zod, Next.js

AI-powered intranet platform with chatbot management (2025)

Role: architecture, AI integration, development

TypeScript, React, tailwindcss, Prisma, Next.js, PostgreSQL, pgvector
OpenAI (ChatGPT, DALL·E), Azure OpenAI, DeepSeek Reasoner
bot management, file upload (SharePoint), vector search, token counting
Chat UI with real-time streaming of user queries and bot responses

Consent management and web analytics with server-side tracking (>6 years)

Role: Conceptualization, Implementation

Consentmanagement (DSGVO), Google Tag Manager (GTM), Google Analytics (GA), Cookie-Handling
Sourcepoint, Tealium, OneTrust
IAB, Vendorlists, Consent Management Platform (CMP): embedding and configuration

AI-assisted application development based on TypeScript, React, Node.js (>8 years) TypeScript, React, Node.js (>8 Jahre)

Role: Lead software development, planning, implementation

agile programming (Scrum, Kanban)
ChatGPT
JavaScript, RxJS, Redux, WebRTC, Next.js
JSON, JSON Schema, YAML, Swagger (OpenAPI)
PayPal REST-API
PostGreSQL, MongoDB, Apache Cassandra, Elastic Search
TRPC, Prisma, Zod, Contentful, Prismic, Apollo GraphQL
GitHub, Github Actions, Atlassian JIRA, Vercel, Docker, Kubernetes (K8s)
Asterisk, Twilio, Vonage (former TokBox) OpenTok.js

Application development with Java / J2EE (>16 Jahre)

Role: Software development, production support

Webservices, SOAP, Struts
XML, XSL
Spring, Apache Ant, Apache Maven, FTP
DB2, Oracle, Structured Query Language (SQL)
IBM RSA, IBM Websphere, IBM Websphere Transformation Extender (WTX)

Microservices architecture with Scala (<3 years)

Task(s): Software development

Microservices, SaaS
Akka, Quill, Kafka

Martin Siegling - Independent expert for AI & consent management