:: SENIOR SOFTWARE ENGINEER ::

Daniel Balcarek

Building practical .NET systems, challenging assumptions with real benchmarks, and exploring where AI actually helps developers.

STATUS: ONLINE // SYSTEM_VERSION: 2026.2

// OPERATOR_PROFILE

I'm a software engineer with 15 years of experience, primarily in C# and .NET. I started with Windows desktop applications and gradually moved into modern web and backend systems. While I also work with Angular, backend engineering, architecture, and performance are where I feel most at home.

I care about clean, maintainable code, but I believe understanding trade-offs is more important than blindly following patterns or best practices. I enjoy questioning assumptions, exploring different approaches, and finding out what actually works through real implementations and benchmarks.

Lately, I've been exploring how AI fits into software engineering, from coding agents and LLM-powered applications to model evaluations and fine-tuning. I'm curious about what's genuinely useful beyond the hype, and I enjoy sharing what I learn along the way, including the things that don't go as planned.

I write about these experiments because I believe useful engineering knowledge shouldn't be unnecessarily complicated.

PORTFOLIO // SELECTED BUILDS

// FEATURED_PROJECTS

Selected applications and technical explorations that demonstrate practical architecture, AI integration, and engineering trade-offs.

SYSTEM DESIGN // AI // PERFORMANCE

// 01. ARCHITECTURE & INTELLIGENCE

Architecture decisions, practical AI engineering, and benchmark-driven investigations grounded in real implementations.

Architecture

API Performance Testing: Designing Realistic Tests

Design realistic API performance tests with representative workloads, external dependencies, production-like environments, and meaningful metrics.
How AI Endpoints Change the Traditional API Flow

How AI-powered endpoints turn a traditional API flow into an orchestration pipeline with validation, retries, and cost controls.
.NET: Vertical Slice vs Clean Architecture — Practical Comparison

Comparison of CA and VSA by real API implementations. Idea of hybrid approaches.
Clean Architecture in .NET: Pros, Cons, and Trade-offs

Honest assessment of Clean Architecture trade-offs based on real project experience.
REST
- Problem Details for HTTP APIs (RFC 9457)
  
  RFC 9457 Problem Details standard and cheat sheet for HTTP API error responses.
- REST API Route Naming Best Practices
  
  REST API route naming conventions: nouns, pluralization, versioning.

AI

I Vibe-Coded My Way Out of Angular Upgrades

Creating an Angular Update Skill for Codex and refining it through real upgrades across three open-source projects.
Polly and the Open Source Maintenance Fee: Funding Open Source

Polly's maintenance fee offers another approach to funding open source while keeping the source license unchanged.
Is AI Changing the World of Open Source?

Reflections on commercial licensing, maintainer workload, security, and how AI may be changing the future of open source.
Old PC vs New AI: Can a 2015 Desktop Actually Run Gemma 4? (2B vs 4B Benchmark)

Benchmarking Gemma 4 E2B and E4B models running locally with Ollama on a 2015 desktop — speed, reasoning, code generation, structured output, and instruction following.
How to Use Gemma 4 E2B the Smart Way: Family Trip Advisor

Building a Family Trip Advisor app with Gemma 4 E2B, ASP.NET backend, and Angular frontend — how smart prompt design and backend orchestration unlock reliable results from small LLMs.
Part 1: Run OpenClaw Locally on Windows Using Windows Sandbox

Part 1: How to safely run OpenClaw on a local Windows machine using Windows Sandbox for secure, isolated AI agent experimentation.
Part 2: OpenClaw Sandbox Guide: One-Click .WSB Setup & AI Provider Comparison

Part 2: Complete OpenClaw setup in Windows Sandbox with automated .wsb configuration and comparison of free and paid AI providers.
The Reality of VibeCoding - Task Manager & Sticky Notes Dashboard

An honest breakdown of why vibecoding is fast but unreliable — and why AI still can't replace real engineering judgment.

Benchmarks

.NET
- Exception vs Result pattern
  
  Benchmark about two error handling approaches.
- CopyTo vs Write
  
  Benchmark about using inner MemoryStream for copy byte array to output MemoryStream.
REFLECTION
- Get Enum Value Attribute
  
  Performance comparison of reflection, cached reflection, and FrozenDictionary for retrieving custom attributes from enum values in .NET 10.
- Export data
  
  Benchmarking reflection-based, cached reflection, and dictionary-based approaches for CSV data export in .NET 10.
- Create Instance
  
  Performance comparison of ServiceProvider, Activator.CreateInstance with concrete type, and Activator.CreateInstance via interface for creating class instances in .NET.

.NET // C# // TESTING

// 02. BACKEND ENGINEERING

Implementation guides, patterns, and testing practices for maintainable ASP.NET Core and C# applications.

ASP.NET

C# Minimal API: A Practical Way to Keep Endpoints Clean

How to keep Minimal API endpoints clean and maintainable using extension methods and RouteGroupBuilder.
C# Minimal API: Multiple Authentication Schemes with Swagger

How to configure JWT and Basic Auth in a Minimal API with working Swagger UI support for each scheme.
Clean Unit Testing in .NET: Practical xUnit and Moq Tips

Practical xUnit and Moq patterns for cleaner, maintainable .NET unit tests.
Secure ASP.NET Core Server Headers

Remove server fingerprinting headers and add Content-Security-Policy, X-Content-Type-Options in ASP.NET Core.
ASP.NET Core Minimal API: Pros and Cons

Where Minimal APIs shine over controllers, and where the trade-offs start to hurt.
Configure ASP.NET Core Options Programmatically

Using delegates and IConfigureOptions for flexible, testable ASP.NET Core configuration.
CACHING SERIES
- ASP.NET Core Caching Strategies Overview
  
  In-Memory, Distributed, Output, Response, and Query caching — when to use each.
- Response Caching vs Output Caching
  
  Side-by-side comparison of where the cache lives and when to use each approach.
- Response Caching in Minimal APIs
  
  Client-side caching headers in ASP.NET Core Minimal APIs using endpoint filters.
- Output Caching with Authorization
  
  Custom Output Caching Policy for authorization header in ASP.NET Core Minimal API.

C#

Remove Diacritics

Extension method to remove diacritics using ISO-8859-8.
Czech encoding in .NET

How to add czech encoding into .NET project.
Enumerable.ZIP

Combine two sequences element by element.
FluentResult UnwrapOrDefault

Extension method for the `Result` object of FluentResult lib.
LINQ: Chaining Two OrderBy Calls

LINQ: Why Chaining Two OrderBy Calls Doesn’t Work the Way You Expect.

// TESTING

Clean Unit Testing in .NET: xUnit & Moq Tips

Practical xUnit and Moq patterns for cleaner, more maintainable .NET unit tests.
Angular: Redefine Property for Jasmine Tests

How to redefine read-only properties on Angular services for unit testing with Jasmine.
Angular: Run a Single Jasmine Test

How to run a single focused test in Angular without running the entire test suite.

ANGULAR // TYPESCRIPT // BROWSER

// 03. FRONTEND DEVELOPMENT

Focused solutions for Angular applications, TypeScript design, browser APIs, localization, caching, and frontend testing.

Angular

HTTP Caching with shareReplay

Efficient HTTP caching with RxJS shareReplay.
Overusing ChangeDetectorRef

Avoid manual change detection anti-patterns.
i18n multiple translation files

Loading multiple translation files in ngx-translate.
Redefine property of mock object

Redefining mock properties with defineProperty.
Run test commands

Cheatsheet for running specific Angular tests.
i18n parameters

Passing parameters to translations in Angular.
package-lock.json in Git

Best practices for package-lock.json and npm ci.

DATABASES // SOURCE CONTROL // OPERATIONS

// 04. DATA & DEVOPS

Practical notes for databases, Git workflows, deployment configuration, package management, and everyday operations.

Configuration

Visible internals from different project

See internal classes from another C# project.
Package json Versioning - Caret

Caret Ranges cheat sheet.
Node.js Version & Dependency Management

Practical guide to switching Node versions with nvm, reinstalling dependencies and configuring npm registries.
K8s, Istio, Argo cheat sheet

Kubernetes, Istio, Argo cheat sheet.

SIDE QUESTS // CREATIVE BUILDS

// 05. EXPERIMENTS & GAMES

Games, coding challenges, and compact experiments built to explore an idea, learn something new, or simply have fun with code.

Challenge Projects

Tower Before Dusk: A Puzzle Game for Humans and AI

A time-limited TypeScript puzzle game that uses WebMCP so humans and AI can attempt the same pathfinding challenge.
Bringing a 2014 WinForms Puzzle Game Back to Life

A nostalgic C# game rebuilt for the browser with TypeScript, responsive canvas rendering, and a little help from GitHub Copilot.
Google Translate Who? An Absurd Text Transformer

A deliberately chaotic Svelte translator featuring speech tools, joke transformations, an evil Clippy, and peak 90s web energy.
A Star Wars Lightsaber Duel in the Terminal

A cinematic Unicode terminal animation built with .NET and GitHub Copilot CLI—because some side quests deserve lightsabers.
msg-rocket: From Diff to Decision with GitHub Copilot CLI

A dependency-free Node.js CLI for smarter commits, staged-code reviews, cleanup checks, and team coding standards.

Daniel Balcarek

// OPERATOR_PROFILE

// FEATURED_PROJECTS

Family Trip Advisor

WeatherApi: Architecture Comparison

OpenClaw in Windows Sandbox

// 01. ARCHITECTURE & INTELLIGENCE

Architecture

REST

AI

Benchmarks

.NET

REFLECTION

// 02. BACKEND ENGINEERING

ASP.NET

CACHING SERIES

C#