Freelancer profile translated to English.
Back to original languageAbout Guido
When companies have systems that don't talk to each other – or software that has grown over years and no one really understands anymore – they come to me.
I am a software architect and technical consultant from Berlin. In over 30 years, I have developed systems from COBOL to ASP.NET Blazor, designed architectures for millions of data points, and analyzed and modernized evolved system landscapes.
What I specifically offer:
🔌 System Integration & Architecture – I connect systems that currently exist as islands: ERP, CRM, production systems, APIs. From conception to implementation, at home in the .NET ecosystem.
🏗️ Software Modernization – From as-is analysis to future-proof architecture. I manage legacy migrations without disrupting ongoing operations.
⚠️ Technical Software Assessment – Before a purchase, acquisition, or fundamental modernization: a well-founded expert report from an architect's perspective.
🤖 AI Integration – I help medium-sized companies identify AI potential and integrate it into existing .NET systems using Azure AI Services.
Who I work for: Medium-sized companies, CTOs, and managing directors who need technical clarity – not more buzzwords.
My Promise: Measurable results. Clear language. No consulting bingo.
📩 Do you have a specific challenge? Write to me directly.
German
Native or bilingual
English
Conversational
Can work on-site
Berlin (up to 50km), Oranienburg (up to 50km)
Experience
- Guido AltmannSoftware Architect – Full-Stack Developer (Demo Project)DIGITAL AND ITJanuary 2026 - February 2026 (1 month)Berlin, Germany**Overview**:Designed and developed a full-stack web application as a reference architecture for maintainable .NET applications with a modern React frontend. The application covers the complete lifecycle of invoices – from creation and management to PDF export. The focus is on clean modularization, domain-driven design, and production-ready infrastructure.In detail:
- Conception and implementation of a modular monolith architecture with clearly separated modules (Users, Invoices, Common) that are loosely coupled and deployed as a single application
- Combination of Vertical Slice Architecture and Clean Architecture: Features are organized by business logic, the domain core remains isolated from infrastructure concerns
- Development of the Invoices module for managing the invoice lifecycle, including PDF export
- Development of a Single Page Application frontend with React 19, TypeScript, and Vite as the build tool, with client-side routing (React Router) for managing invoices, customers, and sender profiles
- Styling with TailwindCSS and use of Zustand for lightweight state management, as well as Axios for API communication
- Reusable UI components for a consistent user experience
- Setup of a complete Docker Compose environment with PostgreSQL, Seq (structured logging), and Jaeger (Distributed Tracing via OpenTelemetry)
- And much more.
- i-digitalSoftware Architect / Technical AssessorCONSULTING AND AUDITSOctober 2025 - October 2025Technical assessment of an established Windows desktop application for auditing and accounting firms.Conducted a comprehensive technical due diligence for a legacy .NET application in the context of a company acquisition. The analysis included assessing the architecture, code quality, maintainability, and technical risks of a business application that had evolved over years with more than 120 productive customer installations.Areas of Focus:• Architecture Analysis: Evaluation of the 3-tier architecture (Data Layer, Business Layer, Presentation Layer) as well as the proprietary ORM framework and the multi-database abstraction layer (VistaDB, MS SQL Server, PostgreSQL)• Code Review: Screenshare-based code walkthrough with the development team, analysis of project structure, build configuration, and version control strategy (SVN)• Risk Assessment: Identification of technical debt, third-party component dependencies, knowledge transfer risks, and modernization potentials• Documentation: Creation of a structured assessment report with prioritized recommendations for the buyerResult:Delivered a well-founded technical expert report as a basis for the acquisition decision, including an assessment of long-term maintainability and effort estimations for identified modernization measures.
- LayTec AGProduct OwnerTECHMarch 2022 - October 2025 (3 years and 7 months)Berlin, GermanyAs a technical Product Owner, I was responsible within the PO team for process-integrated measurement systems in thin-film technology, focusing on the technical evaluation and prioritization of requirements. I translated business needs into actionable solutions, maintained the product backlog, and supported the team with technical expertise.In detail:• Responsibility and prioritization of requirements in the product backlog• Translation of business requirements into clearly understandable user stories and acceptance criteria• Continuous maintenance and prioritization of the backlog, considering business value and technical feasibility• Planning and execution of sprint planning and sprint reviews in a Scrum environment• Responsibility for the functional acceptance of implemented features• Coordination with stakeholders
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Certifications
- CPSA-FiSAQB2018