yagni.dk

Sebastian Bargmann

Senior software engineer in Hørsholm, Denmark

I build software, mostly backend, and run it in production. My work spans application development, DevOps and operations, from near real-time trading systems to platforms I deploy and operate myself.

Operational since 1996

Identity and private communication
Banking
Healthcare
Trading
Software products and web

What I do

Backend
Services, APIs and data layers in C#/.NET, TypeScript and C++
Frontend
Web apps in React and TypeScript, mobile apps in React Native, first steps in Kotlin Multiplatform
Distributed systems
Performance-critical messaging, multicast, multithreading, near real-time data
Delivery
CI/CD pipelines, containers, infrastructure as code with Ansible and AWS CDK, tooling in Python and shell
Observability
Structured logging, correlation IDs, alerting designed to avoid alert fatigue
Operations
Linux, PostgreSQL, SQLite, backup and recovery, incident response
AI-assisted development
AI as sparring partner and as coding agent, with tests, review and CI as the safety net

Work, by area

Identity and private communication

Open-source platform for self-sovereign identity, with end-to-end encrypted storage and messaging. I owned the delivery pipeline, the logging and observability stack, and the server fleet. I still contribute occasionally.

C#, .NET, PostgreSQL, Docker, GitHub Actions, Ansible, Python, OpenTelemetry

Banking

Personal and business banking platforms, internal applications, and AWS infrastructure as code with a disaster recovery design. All of it in regulated environments.

C#, .NET, TypeScript, React, React Native, AWS CDK, Azure, RabbitMQ, Elasticsearch

Healthcare

Co-owner of a clinical outcomes platform for psychotherapy, used by about 5,000 clinicians and staff across Scandinavia. I am solely responsible for its development, operations, security and GDPR compliance for health data. In 2026 I rewrote it from Ruby on Rails to .NET and React, working with AI coding agents, and migrated 15 years of production data.

C#, .NET, TypeScript, React, PostgreSQL, Redis, Docker

Trading

Near real-time trading infrastructure: price distribution over reliable UDP multicast, a message bus for trade and order flow, high-performance market connectivity, and FIX links to external brokers and banks. Six years at one investment bank, which later brought me back twice as a freelancer.

C++, C#, FIX, UDP multicast, multithreading

Software products and web

Remote control and device management software for Windows, Linux and macOS, including Windows kernel drivers. Before and after that, content management and client/server applications.

C++, C#, Qt, Delphi, SQL Server

Contact

sebastian@yagni.dkGitHubLinkedIn