Hi, I'm Michael
Fullstack Developer
Over a decade of experience in software development & consulting - creating clean, maintainable fullstack solutions with Spring Boot & Angular
About Me
Michael Wellner
- Fullstack Developer -
As a Fullstack Developer from Stuttgart, Germany, I build robust, modern backend systems with Spring Boot using Java or Kotlin. My work spans microservice architectures, clean domain models, event-driven integrations, moduliths and high-quality REST APIs. On the frontend side I deliver intuitive Angular applications with a strong focus on usability and maintainability.
With more than a decade of hands-on experience, I have worked across several industries (Automotive, E-Commerce, Finance, Healthcare) and built scalable systems based on Postgres/MySQL, Docker, Kubernetes (Dev), CI/CD pipelines and cloud-ready architecture patterns. I enjoy solving complex technical problems - but always with the goal of creating sustainable, long-term value.
At the moment most of my energy goes into AI-assisted development. I work with Claude Code every day and treat it as part of the toolchain rather than a gimmick: scaffolding services, refactoring older modules, writing tests and reviewing changes. What I find most interesting is where the limits are - which tasks an agent handles reliably, where a developer still has to make the call, and how you keep architecture and code quality intact when code is produced faster than it can be read.
A sabbatical in 2025 gave me the time for a proper tech refresh: Kotlin, Spring Boot 4, Kafka and OpenTelemetry, along with a closer look at Angular 19+ and Kubernetes, rounded off with the OpenTelemetry Certified Associate (OTCA) certification. That habit has stuck - I still believe in continuous learning, pragmatic engineering practices, and a developer culture built on collaboration, code reviews and shared standards.
I thrive in environments where people support each other, knowledge flows naturally, and modern tooling enables focused work. To maintain high concentration and minimize context switching, I often use the Pomodoro technique.
In the complex world of code, simplicity is the ultimate sophistication.
Fullstack Dev
Building scalable backends with Spring Boot (Java & Kotlin) and the Angular frontends that talk to them - one stack, from the database up to the browser.
DB & Messaging
Relational data models in PostgreSQL or MySQL, and event-driven communication over RabbitMQ or Kafka when services should not have to wait for each other.
DevOps
Containers on Docker and Kubernetes, delivery through automated CI/CD pipelines (e.g. Jenkins), and OpenTelemetry so you can see what the system is actually doing in production.
Craft & Tools
IntelliJ IDEA and Git all day, with Claude Code alongside. Clean Code principles and automated tests with JUnit and ArchUnit are what keep the code maintainable.
Professional Journey
Fullstack Software Developer
VYDA GmbH | Remote / Münster
Product development in the personal injury domain: our platform reads large PDF documents using AI and OCR, makes the extracted data reviewable and correctable in modern data entry interfaces, and merges it into one consolidated case file - the basis our medical experts build their assessments on. As one of three fullstack developers I am involved end-to-end: from domain modelling through Spring Boot services in Kotlin and the Angular frontends to deployment and operations on Kubernetes. A team that size leaves a lot of room to shape things - and the responsibility to make architectural decisions that still hold up in two years.
Transition phase & sabbatical
Used the time for a full tech refresh and earned the OpenTelemetry Certified Associate (OTCA). Deepened my expertise in Kotlin, Spring Boot 4 & Spring AI, OpenTelemetry, Angular 19+ and Kubernetes, and took a first look at data science and data engineering.
Team Lead Software Development
sidion GmbH | Remote / Stuttgart
Team lead of an interdisciplinary development team. Built an open team culture through regular meetings and informal virtual exchanges, served as the main contact for professional and personal matters, and handled career development and goal setting.
Senior Software Developer
sidion GmbH | Remote / Stuttgart
Contributed to client projects in the finance and healthcare sectors, mostly Java-based microservice applications. Supported architectural decisions, pushed clean code practices, mentored junior developers, and worked in agile Scrum teams across a broad technology stack.
Professional Software Developer
sidion GmbH | Stuttgart
Worked on client projects across automotive, logistics, banking and e-commerce, mostly Java-based microservice applications on a broad technology stack. Worked in agile Scrum teams, mentored junior developers and pushed clean code practices.
Junior Software Developer
sidion GmbH | Stuttgart
Contributed to a client project in the automotive industry: software development with Java, SQL, XML and IBM DB2. Supported requirements engineering and worked with project management tools like JIRA and Confluence.
Junior Consultant Automotive Engineering
wontec GmbH | Weissach
Worked in product data management at Porsche AG, optimizing product data integration within the Volkswagen Group. Responsible for an interface between SAP and an IBM host, and built VBA tools in Excel for project management and quality assurance.
Skills & Experience
Development
Frameworks & Libs
Tools
Concepts
DB & Messaging
Infrastructure
OS
I primarily develop on macOS for its great developer experience, but prefer Linux (Ubuntu/Debian) for server and container workloads.
Stuff
Other things I have picked up along the way
Recent Projects
MaverickWave
A lightweight CSS framework for responsive websites, with a component set, dark mode and theming through custom properties.
After copy-pasting the same CSS into every side project for years, I finally built the framework I actually wanted to use.
TopoMap
Two agent skills scan your Spring Boot or Angular repo and write a model.json, the viewer at topomap.m1well.com draws it as a map you can click your way through.
Every codebase has a map in it - it just lives in the heads of the people who were there from the start.
Idently
A tiny, stateless, code-based Deno identity server with code login and a JSON client-user store.
Sometimes you don't need OAuth, Firebase, or Keycloak. You just want a damn code and a JWT.
versions
A bash script to display the version numbers of your tools.
I just want to see the version numbers of all my used tools with one command.
Blog Posts
TopoMap - Let an AI Agent Draw the Map of Your Codebase
Every codebase has a map in it, it just lives in the heads of the people who were there from the start. TopoMap pulls that map out of the repo: two Claude Code agent skills read your Spring Boot or Angular project and write a model.json, and a browser-only viewer turns it into a diagram you can click through. No upload, no server, no data leaving your machine.
Atomic Design in Angular: A Scalable Architecture for Modern Applications
Atomic Design splits an interface into atoms, molecules and organisms. Applied to an Angular login screen on v19, with signals and standalone components, and with Nx tags that break the build when someone imports the wrong way round.
Spring Boot 4 - What's New and Why It Matters for Developers
Java 17 as the floor with virtual threads on top, Jakarta EE 11, modular autoconfiguration, and declarative HTTP clients, API versioning and retries moving out of a library and into the framework. With the migration checklist.
Kotlin and Spring Boot for experienced Java developers - A practical introduction
After eight years of shipping services in Java and Spring Boot, I took over a week to really try Kotlin. I expected Java but nicer. What I got is a language that feels familiar in all the right places and surprisingly opinionated where it matters.
Data-Oriented Programming in Java - More Data, Less Magic
Data-Oriented Programming models data as immutable structures and keeps behavior in services. With record, sealed interface and pattern matching, Java 21 makes that idiomatic instead of a workaround. Worked through on payment methods, plus where entities do not fit.
Tired of Auth Overkill? Meet idently - Simple, Stateless Deno Identity Gets Smarter
idently is stateless authentication with Deno that does one thing: a user sends a secret code, they get a JWT back. No email, no password, no session store. Since the first version it also has audience checks, two token lifetimes and custom claims.
MaverickWave - I finally published my own CSS framework
Four weeks, one finished CSS framework, and an honest split of what ChatGPT and Claude contributed against the 80% I had to rework by hand.
My Digital Handshake - Why I Built My Portfolio Page
Why the portfolio page exists, what ended up on it, and why it runs on Astro and my own CSS framework.