kern.services

Available in

Mattanja Kern

Software Architect & Full-Stack Developer

Executive Summary

Software Architect and Full-Stack Developer with over 15 years of expertise in building scalable systems and cloud-native applications.

As a freelancer and former team lead at GFT Technologies, I bring comprehensive experience in architecting and implementing IoT platforms, enterprise applications, and cloud systems. My technical focus lies in .NET/C#, Angular, and cloud technologies, with particular emphasis on Clean Architecture, Domain-Driven Design, and modern DevOps practices. Through my experience across various industries (IoT, Energy, Financial Services) and my ability to master complex technical challenges, I support companies in their digital transformation and the development of future-proof systems. I place particular importance on developing sustainable and maintainable solutions, as well as fostering teamwork and knowledge sharing.

Core Competencies

Enterprise Software Architecture

  • Focus on pragmatic, maintainable solutions
  • Expertise in Clean Architecture and Domain-Driven Design
  • Experience with both traditional and modern deployment approaches

IoT Platform Development

  • Comprehensive experience in IoT data integration and processing
  • Success in both industrial (AXOOM) and energy sector (EnBW) IoT solutions
  • Expertise in real-time data processing and sensor integration
  • Experience with edge computing and cloud integration

Technical Leadership & Team Development

  • Proven track record of leading development teams
  • Strong focus on mentoring and knowledge sharing
  • Experience in both startup and enterprise environments
  • Success in building and maintaining high-performing teams

Curriculum Vitae

Last updated: March 13, 2025

Personal Information

Contact

Personal Details

  • Born: 1982 in Stuttgart
  • Nationality: German
  • Languages:
    • German (Native)
    • English (Fluent / Business Level)
  • Preferred Work Model:
    • 80% Remote, 20% On-site
    • Regular in-person meetings for team collaboration
    • Flexible availability for on-site workshops
    • Effective remote collaboration and communication

Skills & Expertise

Frontend Development

  • Angular, TypeScript, JavaScript, React
  • HTML, CSS, SCSS, Bootstrap, Tailwind
  • Blazor

Backend Development

  • .NET Core, C#, ASP.NET
  • Supabase
  • API-Development, Web Services, SignalR, WPF, WCF
  • NestJS, TypeScript
  • Spring Boot, Kotlin

Cloud & DevOps

  • Docker, Kubernetes
  • CI/CD (Bitbucket, Gitlab, Github)
  • Cloud Platforms (Azure, AWS, Google Cloud)
  • Infrastructure as Code
  • 20 years of Linux server administration experience
  • Container management and Kubernetes cluster administration
  • Cloud-Native (Microservices, Event-Driven Design, Serverless)

AI & Generative Systems

  • Retrieval-Augmented Generation (RAG)
  • Prompt Engineering
  • Integration of AI into Existing Systems
  • Optimization of AI Models for Production Environments

Security & Identity

  • OAuth2/OpenID Connect
  • Identity Server, Keycloak
  • Security Best Practices

Databases & Data Management

  • Data Modeling, Database Design
  • ORMs (Entity Framework, Hibernate)
  • Supabase, MSSQL, MySQL, Oracle, PostgreSQL
  • Data Processing & Analytics

Architecture & Design

  • Clean Architecture
  • Domain-Driven Design
  • Event-Driven Architectures, Messaging, Kafka
  • Microservices Architecture

Testing & Quality

  • Test automation
  • Unit Testing with xUnit, NUnit, Moq, Mockito
  • Frontend Testing with Karma, Jasmine, Cypress
  • Integration Testing and API Testing
  • Test Coverage Analysis and Quality Metrics, SonarQube
  • Test-Driven Development

Project Management & Methodology

  • Scrum, Agile
  • Requirements Engineering
  • Team Leadership
  • Technical Documentation
  • Mentoring and development of junior developers

Additional Skills

  • Linux Server Administration
  • Windows Server & Exchange
  • Git, GitHub Flow
  • Business Process Management
  • Web Services (SOAP, WSDL, XSD)

Industry Expertise

  • IoT & Industrial Automation
  • Energy & Renewable Resources
  • Financial Services & Banking

Development Environments & Tools

  • JetBrains Products (Rider, WebStorm, DataGrip)
  • Visual Studio
  • Visual Studio Code
  • AI Development Tools (Cursor, Copilot)

Professional Development

  • Regular participation in technical conferences and workshops
  • Continuous learning
  • Mentoring junior developers & active knowledge sharing within teams

Education & Certificates

  • 10/2003 – 09/2009 Diploma in Software Engineering, University of Stuttgart
  • 07/2002 Abitur (German High School Diploma)
  • 2019 iSAQB Certified Professional for Software Architecture
  • 2021 iSAQB Advanced Level REQ4ARC, Requirements for Software Architects

Professional Experience

Current Position

Since April 2022 Founder of kern.services software UG Software consulting and development as a freelancer

Previous Positions

2002 – 2022 Side Business – Software Development, Web Hosting, IT Services Software development, creation of small websites, hosting services, operation of various web and mail servers, TYPO3, WordPress

2019 – present rrcenter UG – Association Management Software Co-founder of a company for the distribution of software developed by a team of colleagues for management of a scouts association with person management, event planning, communications and member billing, developed in PHP

2019 – 2022 GFT Technologies SE – Software Architect and Team Lead Software development in customer projects

2015 – 2019 AXOOM GmbH – Software Developer, Lead Developer, and Team Lead Founding member of a TRUMPF startup, development of an IoT platform and IoT applications in mechanical engineering

2008 – 2015 webix solutions GmbH – Software Developer and Lead Developer Initially as a working student, then as a software developer, later as a lead developer with project responsibility in service projects

2005 – 2008 Daimler Financial Services AG / Daimler Chrysler Bank Working student in the development of creditworthiness assessment software

2003 – 2009 University of Stuttgart Software Engineering studies

Project Experience

Current Projects (2022 - present)

ASPION (09/2023 - present) Interim Team Lead, Software Architect, and Lead Developer

  • Led a team of 4 developers in architecting and implementing a scalable IoT cloud platform managing 10,000+ transport sensors
  • Successfully deployed the first version to production after 4 months of development, with continuous feature additions since then
  • Implemented automated deployment
  • Architected a modular monolith serving 30+ enterprise customers
  • Key Technical Achievement: Successfully integrated a legacy system with an external IoT platform by implementing a robust Hangfire job-based architecture, effectively decoupling external system failures from internal processes and ensuring system reliability
  • Technologies: Angular, Cumulocity, .NET Core/C#, Hangfire, Docker, PostgreSQL, Blazor

ENBW (08/2022 - 12/2023) Software Architect and Lead Developer

  • Development of a platform for managing renewable energy generation facilities
  • Key Technical Achievement: Architected and implemented a cloud-native system for calculating wind energy generator yield losses, integrating multiple IoT data sources through Azure Functions and messaging systems
  • Key Technical Achievement: Optimized frontend grid performance by implementing RxJS pipe-based data management techniques including caching, buffering, and background pre-loading, reducing loading times from >10 seconds to <500ms while maintaining full sorting and filtering capabilities
  • Key Technical Achievement: Identified and fixed a critical performance issue in an Azure Function where an exception in a loop caused 5-minute execution times; after optimization, the function completed in 2 seconds
  • Technologies: Angular, .NET Core/C#, Kubernetes, Azure, PostgreSQL, MSSQL, Entity Framework

DEBTVISION (12/2020 - 10/2022) Freelance Software Architect and Lead Developer

  • Architecture and development of a platform for Schuldschein transactions
  • Main Responsibilities:
    • Lead Developer of a second development team focusing on supporting microservices
    • Core architecture team member responsible for managing system dependencies
    • Specification and distribution of team workload
    • Technical Architecture and Design
    • Microservices Implementation
    • Messaging Systems Integration
    • Security and Identity Management
  • Key Technical Achievement: Architected and implemented a comprehensive notification system including:
    • Real-time notifications via WebSocket
    • Chat communication system
    • Email notification service
    • PDF generation service
    • Integration with core Schuldschein (debt obligation bonds) processing system
  • Technologies: Angular, Kubernetes, Spring Boot, Kotlin, PostgreSQL, ActiveMQ Artemis, Keycloak

Previous Projects

Volkswagen Financial Services (07/2019 - 11/2020) Lead Developer

  • Development of multiple projects for vehicle financing applications
  • Technologies: React Frontend, NestJS Services, AWS Lambda, ECS, Fargate, DynamoDB, API Gateway, CloudWatch, IAM, S3

AXOOM GmbH (04/2015 - 06/2019) Software Developer, Lead Developer, Software Architect, Team Lead

  • Development of an Industry IoT Platform (TRUMPF spin-off)
  • Main Responsibilities:
    • Portal for Partner Application Integration
    • Multi-tenant Identity Server with Automated Setup
    • App Store and Automated Installation on Kubernetes Basis
    • Platform Monitoring with Prometheus and Grafana
    • Developer Documentation and Partner Support
  • Technologies: .NET Core/C#, Angular, Kubernetes, Kubernetes Operators, IdentityServer, OAuth2, Google Cloud, GKE, PostgreSQL, Grav, SignalR

webix solutions GmbH (11/2009 – 03/2015) Software Development, Lead Developer

At webix solutions GmbH, I started as a working student and then worked as a software developer and lead developer. During this time, I was responsible for the following projects:

Stuttgart Stock Exchange

  • Order Management Application

    • Development of a securities trading platform
    • Implementation of order management and booking functions
    • High-performance processing of real-time price data
    • Technologies: C# .NET, WPF, WCF, MSSQL, Entity-Framework, proprietary client/server framework

  • Logging & Monitoring Frontend

    • Development of a frontend system for system monitoring
    • Implementation of logging functionality
    • Technologies: C# .NET, WPF, MSSQL, Entity-Framework, proprietary client/server framework

  • GEORGE

    • Near-time quotes and order processing, High-Performance
    • Technologies: Oracle, MSSQL, Triggers, PL/SQL, Stored Procedures

DGNB

  • System Software for Building Certification

    • Further development of building certification software
    • International collaboration with Philippine developer team
    • Technologies: C#, .NET, ASP.NET MVC, Silverlight, MSSQL

  • Navigator for Certified Products

    • Development of a cataloging software
    • Technologies: C#, ASP.NET MVC, MSSQL

Other Customer Projects

  • DOSB (German Olympic Sports Confederation)

    • Development of an XML import system for examination data
    • Technologies: ASP.NET, C#, XmlDataSource, Entity-Framework

  • TechProtect Backbone

    • Development of a workflow management system for marketing services
    • Implementation of multiple registration portals
    • Technologies: C# .NET, WinForms, ASP.NET MVC, jQuery, Telerik Controls, proprietary ORM, Web-Services, Scrum & CI

About Me - Beyond the Professional Resume

I am married and have three children. We live in Eberdingen, a small town in Baden-Württemberg. I enjoy cycling, working out at the gym, playing with my children, woodworking, gardening, and home improvement projects. I also play the violin every few years and enjoy playing chess.

My Mobile Workspace

Due to space constraints at home, I’ve created a unique solution - a fully equipped workspace in a camper van. This isn’t my home, but rather my dedicated office that allows me to work flexibly for clients or enjoy the tranquility of nature while being productive. With a solar panel and a 2kWh battery system, I can work autonomously even on cloudy days. I prefer to work 80% remotely, but I also enjoy working with my customers and colleagues in person. That’s why I’m also happy to be at least once a month in person with my customers.

My Work Philosophy

After 15+ years as a software developer, team lead, and architect at various companies, I’ve been working as a freelancer for the past 3 years. I thrive in collaborative team environments where I can contribute my experience while continuing to learn. I’m particularly passionate about mentoring junior developers and sharing knowledge with colleagues.

My technical foundation includes 20 years of experience operating Linux servers, mail servers, web servers, DNS servers, and various other services. I’ve embraced modern cloud technologies, container management, process automation with CI/CD pipelines, and Kubernetes cluster administration.

Technical Focus Areas

My primary expertise lies in web application development and system architecture, with particular strength in:

  • .NET/C#
  • Angular
  • OAuth2/OpenID Connect
  • Docker
  • Kubernetes
  • AI and Generative Models, Retrieval-Augmented Generation (RAG)
  • Clean Architecture & Domain-Driven Design
  • Event-Driven Architectures, Messaging, Kafka

I prefer working with JetBrains products like Rider, WebStorm, and DataGrip, though I’m equally comfortable with Visual Studio and Visual Studio Code. While AI tools like Cursor and Copilot have significantly boosted my productivity, I firmly believe in mastering the fundamental concepts of software development. In my view, solid software architecture is increasingly crucial for project longevity and data security.

In professional contexts, I quickly grasp and optimize processes across various domains. My experience spans energy supply, logistics, IoT, mechanical engineering, manufacturing, financial services, and stock exchanges.

My Services

Software Architecture

Pragmatic, maintainable architectures using Clean Architecture and Domain-Driven Design for long-term successful solutions.

IoT Platforms

Scalable platforms for industrial and energy sectors with real-time data processing and cloud integration.

Cloud & DevOps

Migration to the cloud, optimization of development processes, and automation with Kubernetes, Docker, and CI/CD pipelines.

Consulting and Software Development

I offer customized consulting and software development services directly at your location.

Complete Projects

Throughout my years of collaboration with various colleagues and companies, I have built a network of experts and can support you in implementing entire projects and help you find suitable partners. This includes software development teams in Germany and the Philippines.

In Brief

I collaborate with both large enterprises and startups, bringing my own ideas and experiences to each engagement. My technical versatility centers on .NET/C#, Angular, Kubernetes, and AI. While I prefer working primarily remotely (80%), I value in-person collaboration with clients and colleagues.

Connect With Me