16+ years
software engineering
Experience with business-critical product and enterprise systems.
Freelance Senior Software Engineer
I modernise complex software systems and unite architecture with delivery.
I support mid-sized businesses and product teams in modernising, stabilising and evolving complex software landscapes. As a Senior Software Architect and Software Engineer, I combine architecture ownership with hands-on .NET and Java engineering.
.NET · Java · Software Architecture · Backend Engineering · Technical Leadership
Stefan Weyer
Architecture · Engineering · Leadership
Experience grounded in delivery
7+ years
technical leadership
As team lead, technical director and CTO.
End-to-end
responsibility
From architecture and implementation to deployment and operations.
Project experience across e-commerce, tax processes, healthcare and veterinary software, and digital platforms.
Typical challenges
When established systems need new clarity.
I step in where domain complexity, technical debt and delivery pressure converge.
Software Architecture
Sustainable architecture decisions for growing or historically evolved systems.
Backend Engineering
Robust APIs, business logic and data models for business-critical applications.
Technical Leadership
Clear technical direction, traceable decisions and practical support for engineering teams.
Modernisation & Integration
Incremental renewal of existing systems without a high-risk wholesale replacement.
Selected case studies
Responsibility is visible in outcomes.
Intentionally anonymised for the public website: focused on the challenge, contribution and technical solution rather than client names.
Digital nutrition consulting platform
- Role
- Lead Software Architect & Full Stack Engineer
- Challenge
- A new digital service required an integrated platform for booking, communication, administration and mobile use.
- Contribution & outcome
- Architecture and delivery of an extensible platform landscape with a shared backend, web applications and mobile apps through to production operations.
E-commerce and tax platform
- Role
- Lead Software Architect & Full Stack Engineer
- Challenge
- Complex e-commerce and tax processes needed to be represented transparently, securely and extensibly in one web platform.
- Contribution & outcome
- Overall technical ownership of a maintainable, testable platform with clear business domains and documented interfaces.
Cloud-based practice management software
- Role
- Senior Software Engineer, .NET & Blazor
- Challenge
- An established practice platform needed regulatory workflows and external integrations without destabilising existing operations.
- Contribution & outcome
- Payment, reporting, appointment and communication processes were integrated into the established business logic and data landscape.
Approach
From understanding the landscape to stable operations.
Architecture is not a separate concept document to me, but the traceable result of sound decisions made through delivery.
- 01
Understand
Capture business goals, existing systems and technical risks.
- 02
Decide
Evaluate architecture options and define transparent guardrails.
- 03
Deliver
Engineer, integrate, test and ship hands-on.
- 04
Stabilise
Secure operations, maintainability, documentation and knowledge transfer.
Career path
Technical leadership built on engineering practice.
My path led from .NET engineering through project and team leadership to CTO. Today, I combine that leadership experience with hands-on architecture and engineering responsibility as a freelancer.
View profile and career →- 01.NET Software Developer
- 02Senior Developer & Project Lead
- 03Team Lead & Technical Director
- 04CTO & Lead Developer
- 05Freelance Software Architect
Contact
Looking for support with a demanding software project?
I support architecture, modernisation, backend engineering and technical leadership engagements across German-speaking Europe — remotely or in a hybrid setup.
- New projects by arrangement
- Remote & hybrid
- Mönchengladbach · North Rhine-Westphalia
- German & English