About

Freelance software product engineer with 15+ years in international e-commerce. I design, build, and ship B2B & B2C systems end-to-end: pragmatic full-stack engineering with a product mindset, in close collaboration with business stakeholders.

On this page

Professional Roles

Product Software Engineer
Full-Stack · Product-Focused

Product delivery from stakeholder requirements to production: full-stack build, infrastructure, and CI/CD included. I work directly with business teams to turn goals into technical decisions.

Lead Engineer
Technical Leadership

Guiding development teams, establishing tech standards, and mentoring engineers while staying hands-on with code.

Solution Architect
System Design

Designing domain-driven architectures, APIs, and cloud infrastructure for e-commerce platforms.

Academic Instructor
Teaching & Mentoring

Teaching business informatics students since 2012, combining theoretical foundations with real-world project experience.

Engineering Principles

Business Alignment
Bridge business goals and technical decisions
Quality
Clean code, backed by tests
Pragmatism
Simple solutions first
AI Leverage
Agents do the routine work, I review
End-to-End Ownership
Problem to production
Security
Part of the design from day one

Agentic Engineering

AI coding agents are a core part of how I build software. Out-of-the-box agents produce generic output, so I design and operate a personal AI coding harness: specialized subagents, custom skills, slash commands, lifecycle hooks, and project context files. With that in place, agents understand the system, follow its conventions, and ship code that fits. I frame the problems, review every diff, and own the architecture and the final result.

Anatomy of the harness

The harness turns a general-purpose model into a tool that knows the codebase and follows its conventions, with a senior engineer reviewing every change.

Specialized Subagents

A fleet of focused subagents (reviewer, test-writer, architect, security auditor, doc writer), each with its own prompt, allowed tools, and permissions. I pick the right specialist for each step.

Custom Skills

Authored skills package recurring expertise, like release notes, schema migrations, accessibility audits, and API doc updates, so it happens the same way every time, with the right tools enabled.

Slash Commands

Reusable team workflows encoded as commands so any teammate gets consistent, audited output.

Lifecycle Hooks

Hooks wired into session start, prompt submit, tool use, and stop events enforce policy, trigger linters and tests, send notifications, and audit activity: guardrails the agent can't bypass.

Context & Settings

Per-repo context files and scoped permissions (CLAUDE.md,AGENTS.md, allow/deny lists) keep the harness predictable, secure, and aligned with the team's standards.

MCP Integrations

Where it pays off, Model Context Protocol servers connect agents to internal docs, APIs, or design tools. Most of the leverage comes from the building blocks above.

Remote Work

I've worked fully remote since 2017, before COVID made it the norm. For me, remote work is about earning trust through reliable delivery and clear, proactive communication. Day to day, that runs on habits: decisions get written down, questions come with enough context to be answered in one pass, and progress stays visible without a status meeting.

Technology Stack

Backend
JavaKotlinSpring BootTypeScriptHonoAstro
Frontend
JavaScriptTypeScriptReactVue.jshtmxAlpine.js
Styling
CSSTailwind CSSUnoCSS
Cloud & Infra
AWSSDKsOpenTofuDocker
Data & Events
MongoDBPostgreSQLKafka
AI & Agents
SubagentsSkillsHooksClaude CodeMCP

Technical Toolbox

Languages & Frameworks

Backend

  • Java, Kotlin
  • JavaScript, TypeScript
  • Spring Boot, Spring Cloud, Spring Security
  • Hono, Astro

Frontend

  • React, Vue.js
  • htmx, Alpine.js
  • Modern CSS
  • Tailwind CSS
Testing & Quality

Testing

  • JUnit Jupiter, Mockito
  • Vitest, Jest
  • Playwright
  • Testcontainers, WireMock
  • RestAssured, Cucumber

Code Quality

  • ArchUnit, JaCoCo
  • ESLint, TSLint, Prettier
  • SonarQube
Build & Deployment

Build Tools

  • Maven, Gradle
  • Bun, npm, Vite
  • Docker, Docker Compose, Podman

CI/CD

  • GitHub Actions
  • GitLab CI
  • Jenkins
Cloud & Infrastructure

AWS Services

  • ECS, EC2, Lambda
  • RDS, DynamoDB, S3
  • API Gateway, CloudFront
  • SQS, SNS, EventBridge

Infrastructure

  • OpenTofu/Terraform, AWS CDK
  • Kubernetes
  • NGINX
Databases & Messaging

Databases

  • MongoDB, DocumentDB
  • PostgreSQL
  • Redis

Messaging & Streaming

  • Apache Kafka
  • RabbitMQ
  • AWS SQS/SNS
Monitoring & Observability

Tools

  • CloudWatch
  • Splunk
  • Datadog
  • Grafana
  • Prometheus
  • ELK Stack
Development Tools

IDEs & Editors

  • IntelliJ IDEA
  • VS Code

Version Control

  • Git, GitHub, GitLab
Additional Libraries

Java Ecosystem

  • Resilience4J
  • Lombok, MapStruct
  • Flyway, Liquibase
  • Swagger/OpenAPI
AI-Assisted Engineering

Tools

  • Claude Code, Claude API, Anthropic SDK
  • Subagents, skills, slash commands, hooks, MCP

Practices

  • Human-in-the-loop review & orchestration
  • Spec-driven development
  • Quality gates

These are the tools I reach for most often. The exact mix shifts with every project.

Teaching & Mentoring

IBS IT & Business School OldenburgSince 2012

Freelance lecturer mentoring business informatics students in recurring courses, and learning plenty from them in return.

Web Applications with JavaScript 2013 - Current

Fourth-semester course where student teams of 3-4 build and deploy their own product. I cover HTTP, API design, modern JavaScript tooling, and Git collaboration.

JavaScriptBunAstroHTMXMongoDBGitHubRailway

Within 2-3 months, student teams build working community forums, survey systems, and booking platforms from scratch.

Software Development with Java 2012 - 2024

Taught freshman and sophomore students Java, from imperative and object-oriented basics through functional programming.

Continuous Learning

Daily Practice

After client work, I turn to books, audiobooks, podcasts, and video courses. Mostly on software development, with regular detours into psychology and how people learn.

Keeping up with the industry is part of my routine. Over the years, though, I've traded broad exploration for deep dives into whatever my current work demands.

Music

To end on a personal note: I love punk rock, pop-punk, emo-punk, and nu metal. After a five-year break, I rediscovered my passion for making music in 2021.

In 2023, I founded Tell All Your Friends as lead singer.

That's it! Reach out on social media or via email. I'd love to hear from you.

Drop a mail

– Jonas