Hendrik Levering
Senior Modernization Engineer – Legacy Web App Performance & Refactoring (Energy Sector)
Experience
Senior Modernization Engineer – Legacy Web App Performance & Refactoring (Energy Sector)
Levering IT GmbH
Re-architected a web application that had grown over years, modularizing tightly coupled components
Reduced response times from several seconds to <50 ms
Removed performance bottlenecks
Simplified architecture so internal teams can implement features on their own again
Senior Backend & Integration Engineer – Legacy Web App and IoT Integration (Energy Sector)
Levering IT GmbH
Modernized an existing platform and built a simple, robust data flow to connect distributed customer systems to an IoT backend
Simplified Kafka/MQTT pipelines and removed duplicates
Expanded observability for reliable near-real-time monitoring and a foundation for predictive maintenance
Lead Developer – SaaS Editor for Organic Shapes (G-Code Generator)
Levering IT GmbH
Developed a browser-based editor with its own slicing engine that enables organic single-wall shapes, checks manufacturability, and generates G-code for 3D printing
Designed a small, easy-to-understand platform with a K3s cluster, Git-based deployments, and observability
Implemented a functional UI for low operational load and easy extensibility
Senior Backend Engineer – Platform for Ecosystem Analysis (Environmental Engineering)
Levering IT GmbH
Built a scalable yet simple backend for asynchronous, long-running compute jobs and external data sources to replace loose script collections
Introduced clear data models and APIs (REST/GraphQL) to simplify onboarding and reduce operational incidents
Owner & Principal Consultant
Levering IT GmbH
Modernized legacy systems, automated and digitized business processes
Developed web-based enterprise applications and internal tools
IT consulting including technical due diligence, system audits, and architecture coaching
Senior Engineer – Expert Suite Usability & Automation (Energy Sector)
Levering IT GmbH
Improving usability and robustness of complex expert software against misuse
Automating manual process chains
Focus on refactoring, CI/CD, and eliminating unnecessary steps in core workflows
Software Developer / Senior Consultant
Siemens / Siemens Energy AG
Development of internal web and desktop applications
Migration of legacy code and data modeling
Building CI/CD pipelines and automation
Conducting internal Python training in the industrial and energy sector
Developing automation tools and NX plug-ins (C#, Python) for parametric CAD models and simulation workflows
Establishing script-based pipelines to optimize manufacturing processes, increasing throughput and process reliability
Summary
Hendrik Levering is a Senior Software Engineer and consultant with over 10 years of experience in modernizing complex, mission-critical systems in energy, industrial, and SaaS environments. He specializes in transforming slow, fragile legacy platforms into clear, high-performing, and maintainable systems – using functional principles, Python, and Clojure. Companies hire him when architecture and infrastructure have spun out of control, response times are measured in seconds, or teams are stuck in over-engineering and slow processes. Hendrik cuts away unnecessary complexity, designs simple data models and system boundaries, and builds internal tools, editors, and automation that drastically simplify development and operations.
Skills
- Legacy Modernization & Refactoring Of Large, Long-lived Systems (Monoliths, Old Web Apps, Desktop Tools, Scripts)
- Performance Engineering (Several Seconds → <100 Ms)
- Simplifying Overloaded Cloud/infrastructure Landscapes (Aws/azure → Focused, Lean Setups)
- Functional Data Modeling, Clear Domain Boundaries, Event-driven Data Flows
- Building Internal Tools, Editors & Automation Systems That Free Up Developer Time
- Lean Ci/cd Pipelines With Short Feedback Loops (Github Actions / Gitlab Ci)
- Technical Due Diligence, System Audits, Architecture Consulting & Team Coaching Through The Modernization Process
- Backend: Python, Clojure, Fastapi, Datomic, Postgres
- Frontend: Clojurescript, React, Vue.js
- Infra: Hetzner, Docker, K3s, Lightweight Kubernetes, Caddy, Linux
- Dev Practices: Functional Programming, Repl-driven Development, Tdd/bdd, Property-based Testing, Solid, Ddd, Clean Code, Continuous Delivery
- Also Experienced With (Used When Needed): Java, C#, Typescript, Node.js, Kafka, Mqtt, Redis, Mongodb, Aws, Azure, Terraform, Devops, Gitops
- Python
- Python2
- Python3
- Senior Python Developer
- Lead Python Engineer
- Clojure
- Clojurescript
- Functional Programming
- Repl-driven Development
- Fastapi
- Django
- Flask
- Microservices
- Legacy Modernization
- Refactoring
- Performance Optimization
- Architecture
- Solution Architect
- Software Architect
- Clean Architecture
- Simplicity-first
- Cloud Migration
- Aws
- Azure
- Kubernetes
- K3s
- Docker
- Ci/cd
- Github Actions
- Gitlab Ci
- Postgres
- Datomic
- Rama
- Graphql
- Rest
- Event-driven
- Kafka
- Mqtt
- Iot
- Internal Tools
- Developer Productivity
- Automation
- Editors
- Computational Systems
- Saas
- B2b Saas
- Energy Sector
- Industrial Iot
- Environmental Engineering
- Consulting
- Technical Lead
- Lead Engineer
- Principal Consultant
- Freelance
- Contractor
- Sql
- Postgresql
- Llm
Languages
Education
Dual IHK apprenticeships as Industrial Mechanic · Industrial Mechanic · Germany
Westfälische Hochschule
M.Eng. Mechanical Engineering · Mechanical Engineering · Germany
Universität Duisburg-Essen
Supplementary studies · Applied Computer Science · Essen, Germany
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