~10 yearsBackend engineering
Building maintainable systems in C# and .NET.
Senior .NET Backend Engineer
DenisŠijanov
I design and build software that is easy to understand, maintain, and evolve.
I have nearly ten years of experience building backend systems in C# and .NET. My interests include software architecture, automation, and AI-assisted software development.
Tech stack.NETC#SQL ServerEntity FrameworkWPF / MVVMFeature flags
Production systemsC#, .NET, SQL
Billing, finance workflows, and operational business logic.
ArchitectureMaintainable systems
Systems built to keep evolving safely.
Currently buildingAI Factory & AI Coach
Autonomous engineering & AI-assisted productivity.
Experience
- MMewsBilling & Finance backend
Business-critical billing, taxes, and finance systems in a large C#/.NET platform.
- UUnicode SystemsHead Office / Back Office
Operational business systems — backend business logic, APIs, and database work in C#/.NET and SQL Server.
- GGOPASStoryBoard (WPF / MVVM)
Desktop application for building interactive software tutorials and training lessons.
- AAtosFirst professional role
Team-based development inside an existing enterprise C#/.NET codebase.
Currently working on
- AI FactoryActive project
An autonomous software development platform for planning tasks, running coding agents, and creating pull requests.
- AI CoachActive project
A personal planning and reflection application connecting daily plans, tasks, habits, and journaling.
- Staff engineering and API designCurrently exploring
Studying wider technical influence and how backend APIs work as stable, understandable contracts.
Featured projects
All projectsActive
AI Factory
An experimental system where AI agents help move a real repository forward: selecting tasks, implementing changes, opening pull requests, and feeding lessons from each run back into the process.
Active
AI Coach
A personal beta application for planning the day, capturing reality, and reflecting on where time and energy actually go.
Mews / Billing & Finance
Historical correctness of accounting categories
How we stopped calculating the accounting category from the current configuration and started storing it so historical reports would stay stable.
Mews / Billing & Finance
Separating the Billing domain inside a monolith
A proposal for gradually clarifying Billing boundaries inside an existing monolith.
Mews / Billing & Finance
Feature Flag Runner
How I turned a feature flag into more than a boolean switch: a tool for rollout, logging, measurement, and result comparison.
GOPAS
StoryBoard
An internal WPF/MVVM application that captured screens and UI elements from other programs and turned them into interactive software tutorials.
Latest writing
Engineering notebookHow Could the AI Race End?
A walk through the possible outcomes of the AI race—from useful tool to singularity—and the harder question of who controls the technology and to what end.
Jak poznat, co se učit a zda tomu skutečně rozumím
Learning note o tom, jak si stavím vlastní systém učení — od cíle přes vzor a schopnosti až k ověření a záznamu porozumění.
Professional focus
Complex business systems.
My strongest work is in existing systems where domain rules, data correctness, backward compatibility, and safe rollout matter.
How I think
Understand before changing.
I care about root causes, explicit business rules, automation that remains understandable, and systems that can keep evolving.
Let's build something great together
I'm open to interesting problems and long-term collaboration. Feel free to reach out.