Welcome to

fehn.systems

Your partner for digital transformation with 12 years of industry experience

Services

Services.

Software architecture & development

I design and build tailor-made software solutions: from initial architecture to production-ready application. With over a decade of full stack experience, I help you choose the right technologies and structure your system for long-term maintainability. Whether you need a greenfield product or an extension of an existing platform, I work closely with you to turn requirements into clean, scalable code. I cover the entire stack: backend services, APIs, databases, and modern frontend interfaces. The result is software that fits your business exactly, not a generic off-the-shelf product.

System migration

Outdated systems slow down your business and accumulate hidden risk over time. I help you move from legacy software to modern, maintainable platforms without disrupting your daily operations. Each migration starts with a thorough analysis of your existing system, data structures, and integrations to build a solid transition plan. I guide the process step by step, ensuring data integrity and minimizing downtime throughout. The end result is a future-proof system your team can confidently build on.

AI consultation

AI is reshaping how businesses operate, but not every tool or hype cycle is right for your situation. I help you cut through the noise and identify where AI can deliver real, measurable value in your workflows. From evaluating large language models to designing AI-assisted features and automation pipelines, I translate technical possibilities into practical solutions. I work with you to assess feasibility, manage expectations, and implement responsibly. You get honest, vendor-neutral advice grounded in hands-on experience.

Workshops

Knowledge is the most durable investment a team can make. I offer focused, hands-on workshops on topics like modern software architecture, full stack development, and practical AI integration. Sessions are not generic slide decks but tailored to your team's experience level and the specific challenges you face. Participants leave with concrete skills and actionable patterns they can apply immediately. Whether it's a half-day deep dive or a multi-day training, I adapt the format to what works best for you.

Projects

Projects.

Here are some projects I recently worked on:

Product Data Research & Ordering Platform

I developed a complete end-to-end web platform for automotive parts operations: one part for web-based item research and flexible exports, and another for warehouse and ordering workflows. The system integrates external data sources to support manual, scheduled, and SFTP-based exports, cart-driven ordering, order imports from external systems, and returns/backorder management.

Exporting very large datasets (multi-million records) is significantly faster than a previous implementation, while also improving data correctness by sourcing data through external services. Export files can be delivered directly to an SFTP server for downstream processing.

Orders prepared in external systems can be imported in multiple formats and processed directly. Users can view and cancel backorders, and request returns and track their status end-to-end.

Enabled customized exports of different output formats with selectable fields and order
Listing of customer-individual prices and stocks of products
Implemented cart management and streamlined ordering workflows
Added support for importing orders prepared in external systems (multiple formats)

Main technologies: DockerNode.jsSOAPSQLiteMS SQL ServerSvelteKitTypeScript

Internal Admin Tool for Master Data Curation

I built an internal admin web app for maintaining and curating master data in an automotive parts catalog. It helps employees manage items, suppliers/brands, and the associated cross-references in the connected data store. The UI is tailored to internal master-data workflows.

Due to the customization to the client’s needs, efficiency in data maintenance was significantly improved, reducing daily manual tasks by up to 25% in time.

Analyzed existing master data workflow patterns
Enabled bulk editing of master data records
Supported importing and exporting master data for downstream processes

Main technologies: DockerNode.jsMS SQL ServerSvelteKitTypeScript

Booking & Workshop Platform

I modernized a platform for booking workshop appointments where customers use a booking widget to choose their vehicle, select services and a workshop, enter their details, and confirm a booking. Workshops manage appointments in a dashboard (accept, cancel, mark as completed), retrieve additional vehicle details, add required spare parts to an external cart, and can self-register to join the network.

After migrating the platform, every key interaction became dramatically faster and more user-friendly for end customers, workshop owners, and admins. The system is now significantly easier and faster to extend, enabling external services to be integrated via standardized REST and GraphQL interfaces.

Enhanced the existing React widgets and frontend
Migrated microservices to a more efficient monolith
Implemented new database & admin UI

Main technologies: DirectusDockerGoGraphQLNode.jsPostgreSQLReactSvelteKitTypeScript

About me

About me.

Andreas Fehn

Senior Full Stack Engineer Open Source Enthusiast

Husband Father

During my computer science studies, I started in 2014 supporting young companies on their digital journey to success and helping established businesses navigate their digital transformation.

To do this, I specialized in full stack development: building complete solutions that deliver real value to clients through tight integration.

When I find time outside of work and family, I contribute to open source projects and enjoy hitting the gym.

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