IT architecture & system design
Designing scalable system and cloud architectures, reviewing existing landscapes, planning migration and modernization strategies.
IT architecture · IT consultingCologne, DE
Stefan Reuter
Freelance IT consultant and architect based in Cologne, Germany. I help teams design, build and operate systems that hold up over time.
§ 01 /About
I support companies as a freelance IT architect and consultant – independent since 2008, previously seven years as a business analyst and IT architect at Postbank Systems. From architecture through program management to operations.
Clients value pragmatic decisions, clear communication and solutions that remain maintainable long after the project ends. I work closely with engineering teams, CTOs and business stakeholders — often as a bridge between the two worlds.
- Experience
- Independent since 2008 · IT since 1996
- Industries
- Banking · Insurance · Retail · Media · Telecommunications · Air traffic management
§ 02 /Services
From the first whiteboard sketch to production.
[01] [02] IT consulting
Technical advice for management and engineering teams: technology selection, roadmaps, effort estimation, second opinions.
[03] AI & LLM integration
Assessing and integrating AI and LLM components into existing systems: feasibility, architecture, data protection and production readiness.
[04] Program & project management
Leading transformation projects and multi-year IT programs – from roadmap and governance to operational delivery.
[05] Cloud & operations
Building and hardening cloud environments (AWS, Kubernetes), infrastructure-as-code, observability and operational concepts.
[06] Software engineering
Hands-on development where it matters: prototypes, critical components, refactoring and technical leadership inside your team.
§ 03 /Training
Hands-on knowledge straight from the trainer – compact, practical, on-site on request.
- Workshop · 2 days
Local & agentic AI
On-premise · air-gappedAI in your own data center instead of the cloud – for sensitive data, regulated and security-critical environments up to a full air gap. From open models and local inference through hardened RAG to agentic systems: how to control agents and harnesses with tool access, secure them with guardrails and operate them in line with GDPR and the EU AI Act.
- On-premise
- Air-gapped
- Open models
- Local inference
- vLLM & Ollama
- Local RAG
- Agentic AI
- Tools & harness
- Guardrails
- LLM security
- GDPR & EU AI Act
- GPU operations
- Workshop · 3 days
Domain-Driven Design
Make complex business domains manageable: strategic design with subdomains, bounded contexts, ubiquitous language and context mapping, plus tactical design with aggregates and domain events. With event storming, microservice architecture and hands-on implementation – including the common pitfalls.
- Strategic design
- Subdomains
- Bounded contexts
- Ubiquitous language
- Context mapping
- Tactical design
- Aggregates
- Domain events
- Event storming
- Microservices
- Implementation
DDD & AIRequest trainingDomain-Driven Design pays off especially in the age of AI: cleanly separated bounded contexts and an unambiguous ubiquitous language give AI coding assistants and LLM-based systems the domain context and guardrails they need to work reliably against the right model.
- Workshop · 2 days
Keycloak
Keycloak 26Single sign-on with Keycloak from the ground up: from OpenID Connect, OAuth 2.0 and SAML through realms, clients and user management to themes, plugins and running it in production on a cluster. With hands-on labs on a real Keycloak instance.
- SSO
- OIDC & OAuth 2.0
- SAML
- Realms & clients
- Users & LDAP
- External IdPs
- MFA
- Themes & plugins
- REST admin API
- Operations & clustering
§ 04 /Projects & Companies
Projects and companies I'm involved with.
§ 05 /Contact
Interested in working together, or just have a quick question? I'd be glad to hear from you.
- GitHub
- github.com/srt