.NET & C# Development

C# 12 Crash Course — Everything You Actually Need

Project: Scaffold OrderFlow from Zero to Running API

REST Rules Senior Devs Follow (That Juniors Don't)

Stop Returning 200 for Everything — HTTP Status Done Right

Kill the Hardcoded Values — appsettings.json & Env Vars

Understand DI by Building It Without a Framework First

Lab: Break Your App With Wrong Lifetimes — Then Fix It

Keyed Services — Register Multiple Implementations Cleanly

Register 50 Services in 2 Lines Using Scrutor

Build Custom Middleware That Logs Every Incoming Request

Stop Repeating Auth Logic — Add Action & Exception Filters

Never Return a Raw 500 Again — ProblemDetails & Global Errors

Add Serilog in 10 Minutes — Logs Your Team Can Search

Build Your First Real Endpoint — Minimal API vs Controllers

Wire Up Controllers, Routing & Auto-Generated Swagger Docs

Minimal API Deep Dive — Group, Validate & Document Endpoints

Version Your API So You Never Break Clients Again

Generate Beautiful API Docs with OpenAPI & Scalar

IEnumerable vs IQueryable — Stop Pulling 100k Rows You Don't Need

EF Core from Scratch — Map Your First Database Table

Fluent API — Configure Entities Without Polluting Your Domain

Relationships Done Right: 1-to-1, 1-to-Many, Many-to-Many

Build Paginated, Sorted & Searchable Endpoints

Add Soft Deletes in 5 Minutes With Global Query Filters

Bulk Insert 10,000 Rows Without Killing Your Database

Prevent Lost Updates — Optimistic Concurrency in Practice

Wrap Multiple Operations in One Safe Transaction

Intercept Every Save — Add Audit Trails Automatically

Lazy vs Eager Loading — What's Silently Killing Performance?

Challenge: Find & Fix the N+1 Query in This Controller

When EF Core Isn't Enough — Raw SQL, Dapper & Stored Procs

API Key Auth in 15 Minutes — Simple, Effective, Secure

Build JWT Auth from Zero — No Libraries, Just Code

Add Refresh Tokens — Sessions That Survive Expiry

Lock Down Endpoints With Roles & Custom Claims

Policy-Based Auth — Complex Rules Without Spaghetti Code

OAuth 2.0 & OpenID Connect — Let Others Handle Auth

Rate Limit Your API Before It Gets Hammered

Fix CORS Errors Forever — Plus Add Security Headers

Security Middleware & Filters in Action

Milestone: Secure the Entire OrderFlow API End-to-End

Options Pattern — Strongly-Typed Config With Validation

Validate Requests With FluentValidation — Zero Boilerplate

Result Pattern — Stop Using Exceptions for Flow Control

Repository & Unit of Work — Do You Actually Need It?

Repository + Unit of Work — The Real Production Implementation

CQRS With MediatR — Commands, Queries, Pipeline Behaviors

Decorator Pattern — Add Caching Without Touching Business Logic

Specification Pattern — Move Query Logic Out of Controllers

AutoMapper vs Mapster vs Manual — Which Is Worth It?

Domain Events — Decouple Side Effects From Your Core Logic

Outbox Pattern — Never Lose a Message on DB Failure

Feature Flags — Ship Code Without Switching It On

Build a Webhook System — Event-Driven API Communication

SOLID Principles in Real .NET Code (Not Just Slides)

Clean Architecture — Structure an API You'll Be Proud Of

Vertical Slice — One Feature, One Folder, Zero Friction

DDD in .NET — Rich Domain Models That Express Business Rules

Modular Monolith — Clean Boundaries Without Microservice Pain

Challenge: Should OrderFlow Become Microservices?

Add In-Memory Cache — Cut DB Calls on Hot Endpoints

Redis Cache-Aside Pattern — Scale Beyond One Server

Output Caching — Serve Responses Without Touching Your Code

HybridCache — L1 + L2 Caching With Stampede Protection

Compress API Responses — Halve Your Payload Size

Stream Large Datasets With IAsyncEnumerable

Zero-Allocation Code — Span<T>, ArrayPool & Object Pooling

Measure Before You Optimize — BenchmarkDotNet in Practice

Challenge: Profile & Fix This Slow OrderFlow Endpoint

IHttpClientFactory — Never Leak Sockets Again

Refit — Call External APIs Like Invoking a C# Method

Polly — Retry, Circuit Breaker & Hedging for Flaky APIs

Delegating Handlers — Propagate Auth Tokens Automatically

IHostedService — Run Work in the Background Without a Queue

Scheduled Jobs With Quartz.NET — Fire at 2am, Not 2pm

Hangfire — Retry Failed Jobs & Watch Them on a Dashboard

Worker Services — Standalone Background Processors

Secure File Uploads — Validate Type, Size & Malware Risk

Upload to Azure Blob — Generate SAS URLs on Demand

Generate PDFs & Excel Reports on the Fly

Push Live Order Updates to the Browser With SignalR

Health Checks — Know If Your API Is Sick Before Users Do

OpenTelemetry — Trace a Request Across Every Layer

Centralized Logs With Seq — Search 10,000 Lines in Seconds

Prometheus + Grafana — Build a Live Dashboard for Your API

Unit Test Your Handlers — Fast, Isolated, Reliable

Integration Tests That Hit a Real Database

Testcontainers — Spin Up Postgres & Redis in Your CI Pipeline

Project: Ship OrderFlow — Docker, CI/CD & Zero-Downtime Deploy

YARP Gateway — Route, Load Balance & Authenticate at the Edge

Interview Prep: Junior .NET (Q1–Q80)

Interview Prep: Senior .NET (Q81–Q250)