kern.services

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Mattanja Kern

Software Architect, Developer & Team Lead

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Executive Summary

Software Architect, Developer & Team Lead with over 15 years of experience in professional software development. Project experience at ASPION, LBBW, EnBW, Börse Stuttgart, TRUMPF, Daimler Financial Services, and more. Successful project implementation from inception to long-term operation in well over 15 projects. Fullstack developer with deep technical understanding of the entire stack.

Skills & Knowledge

Software Development

  • .NET & .NET Core (C#), Angular, Angular Material, CSS, Hangfire
  • API Design, Database Layout, SQL, AI, RAG, MCP-Server, Git, Clean Code

Operations

  • Kubernetes (Setup & Deployment), Backup Management, Security, GDPR
  • Linux Server Administration, Terraform, Flux CI/CD

Project Management & Team Leadership

  • Tech Lead, Scrum, Servant Leadership & Team Development
  • Requirements Engineering

Frontend Development

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

Backend Development

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

Cloud & DevOps

  • Docker, Kubernetes, Helm
  • CI/CD (Bitbucket, Gitlab, Github), Terraform, Infrastructure as Code
  • Cloud Platforms: Azure, AWS, Google Cloud
  • 20 years Linux server administration
  • Container management, Kubernetes cluster administration
  • Cloud-native (container orchestration, microservices, event-driven, serverless)

AI & Generative Systems

  • Retrieval-Augmented Generation (RAG), MCP-Server implementation
  • Integration of AI into existing systems
  • Optimizing AI models for production

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

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

Testing & Quality Assurance

  • Automated Testing, xUnit, NUnit, Cypress, Karma, Jasmine
  • Mocking: Moq, Mockito
  • Test-Driven Development

Project Management & Methods

  • Scrum, Agile, Requirements Engineering
  • Team Leadership, Mentoring 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 & Renewables, Financial Services & Banking

Development Environments & Tools

  • JetBrains (Rider, WebStorm, DataGrip), Visual Studio, VS Code
  • AI tools: Cursor, Copilot

Professional Development

  • Regular participation in technical conferences and workshops
  • Continuous learning, mentoring, and knowledge transfer

Degree and Certificates

  • 2009 Diploma in Software Engineering, University of Stuttgart
  • 2019 iSAQB Certified Professional for Software Architecture
  • 2021 iSAQB Advanced REQ4ARC, Requirements for Software Architects

Professional Experience

Current Position

Since April 2022 kern.services software UG – Software consulting and development on a self-employed basis (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 – today rrcenter UG – Association management software: Co-founding of a UG for the distribution of software developed with several colleagues for association administration, person management, event planning, communication and member accounting, developed in PHP
  • 2019 – 2022 GFT Technologies SE – Software Architect and Team Leader: Software Development in Customer Projects
  • 2015 – 2019 AXOOM GmbH – Software developer, lead developer and team leader: 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: First working student, then software developer, later lead developer with project responsibility in service projects
  • 2005 – 2008 Daimler Financial Services AG / Daimler Chrysler Bank: Working student in the development of software for credit checks

Project Experience

Current Projects (2022 - Present)

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

  • Led a team of 4 developers in the architecture and implementation to connect sensors to an IoT cloud platform to manage over 10,000 transport sensors
  • Successful go-live of the first version after 4 months of development, continuous expansions since then
  • Implementation of automated deployment processes, architecture of a modular monolith for over 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, Unit-Testing, Moq, Jasmine

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

  • Development of a platform for the management of plants for electricity generation from renewable energies
  • Key technical achievements:
    • Architecture and implementation of a cloud-native system for calculating wind turbine yield losses, integrating multiple IoT data sources via Azure Functions and messaging systems
    • Optimize front-end grid performance by implementing RxJS pipe-based data management techniques such as caching, buffering, and background preloading, reducing load times from >10 seconds to <500ms while fully retaining sorting and filtering capabilities
    • Identify and fix a critical performance issue in an Azure Function where an exception in a loop resulted in 5-minute execution times; after optimization, the function was completed in 2 seconds
  • Technologies: Azure, Azure Functions, App Services, Azure Databases, Application Insights, .NET Core/C#, xUnit, Angular, Storybook, Cypress, KendoUI, NX, Kubernetes, PostgreSQL, MSSQL, Entity Framework

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

  • Architecture and development of a platform for Schuldschein transactions
  • Lead developer of a second development team with a focus on supporting microservices
  • Member of the core architecture team responsible for the management of system dependencies
  • Specification and distribution of the team workload, technical architecture and design, implementation of Microservices, Messaging System Integration, Security, and Identity Management
  • Key technical achievement: Architecture and implementation of a comprehensive notification system, including: real-time notifications via WebSocket, chat communication system, email notification service, PDF generation service, integration with the core promissory note processing system
  • Technologies: Angular, Kubernetes, Spring Boot, Kotlin, PostgreSQL, ActiveMQ Artemis, Karma/Jasmine Testing, Keycloak

Previous Projects & Employers

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

  • Development of several projects to apply for vehicle financing
  • Technologies: React Frontend, NestJS Services, Cypress Tests, AWS Lambda, ECS, Fargate, DynamoDB, API Gateway, CloudWatch, IAM, S3

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

  • Development of an Industry IoT platform (TRUMPF spin-off)
  • Portal for integration of partner applications
  • Multi-tenant identity server with automated setup
  • App store and automated installation based on Kubernetes
  • 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, Bootstrap CSS

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

  • Order Management Application for Börse Stuttgart: Trading platform for securities, order management, booking, high-performance real-time price data
  • Logging & Monitoring Frontend for Börse Stuttgart: System monitoring, logging
  • GEORGE for Börse Stuttgart: Near-time quotes and order processing
  • DGNB: System software for building certification, international cooperation
  • DGNB: Navigator for certified products, cataloging software
  • DOSB: XML import system for exam data
  • TechProtect Backbone: Workflow management system for marketing services, registration portals
  • Technologies: C# .NET, WPF, WCF, MSSQL, Entity Framework, Oracle, PL/SQL, ASP.NET MVC, Silverlight, jQuery, Telerik, proprietary frameworks, Scrum & CI

About Me

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