Custom Backend Systems
Scalable Go backends, distributed systems, and APIs with focus on performance, clean architecture, and cloud-native deployment.
Alexander Ertli
Software Engineer • Go & Cloud-Native Systems
Custom software engineering specializing in Go, building scalable backend systems, AI-native applications, and cloud infrastructure with full-stack capabilities.
What I Build
AI-Native Applications
RAG pipelines, LLM orchestration, and workflow engines with explicit state management and audit trails built on robust Go backends.
Cloud Infrastructure
Secure, observable distributed systems on Kubernetes with compliance and governance built-in.
Experience
Apr 2025 – Nov 2025
Contenox — AI & Technology Solutions
Technical Lead · Hamburg (Hybrid)
- Built open-core GenAI platform (12+ services): declarative workflow engine, RAG systems, multi-provider model routing, and admin UI.
- Architected and developed the full runtime stack in Go: vector search, RAG, task & tool orchestration, and multi-model routing.
- Platform development discontinued in November 2025; technology and expertise available for new projects.
Feb 2023 – May 2025
Senior Software Developer (L4)
Direktiv.io · via Remote Technologies GmbH
- Feature owner for event bus & observability on Kubernetes-native workflow engine using OpenTelemetry and Fluent Bit.
- Developed REST/SSE APIs with OpenAPI, managed monorepo CI/CD, and multi-cloud Kubernetes deployments.
- Implemented ABAC patterns and security hardening across distributed systems.
Aug 2022 – Jan 2023
Python Engineer (DevSecOps/MLOps)
T-Systems on site services GmbH
- Vulnerability management & security compliance; CI security gates and container hardening.
- Python microservices on Kubernetes; data pipelines and monitoring systems.
2013 – 2022
IT Systems Consultant
Hamburg (On-site)
- Multi-site network architecture and security across 60+ deployments; ISDN → VoIP migrations and enterprise WiFi with segmentation.
- Data protection risk assessments and IT asset governance.
Engineering Principles
- Clean Architecture Well-structured Go backends with clear separation of concerns, testability, and maintainability.
- Observability First Traces, metrics, logs — built-in before scale-up for debuggable systems.
- Security by Design Least-privilege access, audit trails, and compliance built into every layer.
- Clean Handovers You own the code, documentation, and operational runbooks.
- Open Standards Avoid vendor lock-in with portable, standards-based architectures.
Education & Certifications
B.Sc. Computer Science
University of Bremen
Graduated Jun 2022
Selected Projects
- Developer Workflow Navigation & Analytics (Apr 2021 – Apr 2022)
- Speech Recognition for a Digital Assistant (Oct 2019 – Aug 2020)
Certifications
- AWS Technical Essentials
- Scrum Master Basics (onsite academy)
Languages
- German (native), Russian (native), English (fluent)
Technical Expertise
Custom Backend Engineering
Go, PostgreSQL, event-driven systems, distributed architecture, API design, performance optimization
AI/ML Systems
LLM orchestration, RAG pipelines, vector search, workflow state machines, multi-provider routing
Cloud Native
Kubernetes, Docker, OpenTelemetry, CI/CD, multi-cloud deployment
Security & Compliance
ABAC, OIDC/OAuth2, audit logging, EU-ready governance, vulnerability management
Frontend & UX
React/TypeScript, workflow visualization, dashboard design, real-time interfaces
Infrastructure
Network engineering, VoIP systems, cloud infrastructure, distributed systems
Contact
Let's discuss your project
Whether you're building a new backend system, integrating AI capabilities, or optimizing your infrastructure, I'd love to help.
📍 Hamburg, Germany