About
Freelance product software engineer with 15+ years in international e-commerce. I design, build, and ship B2B & B2C systems end-to-end — combining pragmatic full-stack engineering with a product mindset.
Professional Roles
End-to-end product delivery from problem framing to production — full-stack build, infrastructure, and CI/CD included. AI coding agents in the loop for leverage and speed.
Guiding development teams, establishing tech standards, and mentoring engineers while staying hands-on with code.
Designing scalable domain-driven architectures, APIs, and cloud-native solutions for e-commerce platforms.
Training next-gen software engineers, combining theoretical foundations with real-world project experience.
Remote Work
Working remotely since 2017 (pre-COVID), I've mastered asynchronous communication, self-organization, and seamless collaboration. For me, remote work means earning trust through reliability and clear communication — delivering results consistently without needing oversight.
Engineering Principles
Software engineering is empirical discovery and design. I embrace modularity, cohesion, separation of concerns, and loose coupling to manage complexity.
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. Agents understand the system, follow conventions, and ship code that fits. I stay in the driver's seat — framing problems, reviewing diffs, owning the architecture and the final result. It's AI leverage, not AI autopilot.
The harness is what turns a general-purpose model into a teammate that knows your codebase — and what keeps me, the senior engineer, firmly in the loop.
Specialized Subagents
A fleet of focused subagents — e.g. 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 — release notes, schema migrations, accessibility audits, 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
CLAUDE.md, AGENTS.md, scoped permissions, allow/deny lists, and per-repo settings keep the harness predictable, secure, and aligned with your team's standards from day one.
MCP Integrations
Where it pays off, Model Context Protocol servers connect agents to internal docs, APIs, or design tools. Selectively added — most of the leverage comes from the building blocks above.
Technology Stack
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 Harness
Harness Components
- Specialized subagents
- Custom skills & slash commands
- Lifecycle hooks
- Context files
- Scoped permissions & settings
- MCP integrations (where useful)
AI Agents
Coding Agents
- Claude Code
- Claude API, Anthropic SDK
AI Practices
Practices
- Human-in-the-loop review & orchestration
- Context engineering
- Spec-driven development
- Quality gates & senior judgment
The lists above represent my frequently used toolset. I continuously adapt to project requirements and I am always learning new technologies.
Continuous Learning
After client work, I immerse myself in technical literature, audiobooks, podcasts, and video courses focused on software development, learning methodologies, psychology, and personal growth.
Staying updated with industry developments and trends is second nature. I've shifted from broad exploration to deep dives into current challenges relevant to my work.
Teaching & Mentoring
Regular freelance academic trainer mentoring business informatics students across multiple semesters. Interactive, collaborative teaching focused on mutual learning.
Web Applications with JavaScript 2013 - Current
Fourth-semester course where student teams of 3-4 build real-world projects from scratch. I cover HTTP, API Design, modern JavaScript tooling and Git collaboration.
Students' creativity and teamwork consistently surpass market solutions within 2-3 months, building community forums, survey systems, and booking platforms.
Software Development with Java 2012 - 2024
Taught and mentored freshman/ sophomore students in Java programming, covering procedural, imperative, functional, and object-oriented paradigms.
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! Feel free to reach out on social media or via email. I'd love to hear from you!
Drop a mail– Jonas