Learn C# the way it’s written now.Real .NET tests. Modern C#. No videos.
Three courses that take a working programmer from records, pattern matching and LINQ to ASP.NET Core APIs and production ops. Every exercise is graded by real xUnit tests running on .NET — so “it works” is never a vibe. Built for people who already program, not WinForms-era tutorials.
// Classify each payment and total the refunds.
// The grader runs real xUnit tests against your code.
public record Payment(string Id, decimal Amount, string? Coupon);
public static string Describe(Payment p) => p switch
{
{ Amount: < 0 } => "refund",
{ Coupon: not null } => "discounted",
{ Amount: >= 100m } => "large",
_ => "standard",
};
public static decimal RefundTotal(IEnumerable<Payment> payments) =>
payments
.Where(p => Describe(p) == "refund")
.Sum(p => -p.Amount);Language, LINQ & Async
Modern C# for people who already program — records, pattern matching, nullable reference types, LINQ, and async/await, graded by real .NET tests.
Web APIs, Data & Testing
Tested, database-backed HTTP services — ASP.NET Core handlers, EF Core with Postgres, xUnit testing, and auth.
Background, Ops & Capstone
The production tier — background workers and channels, observability, Docker & CI, and the LaunchBoard capstone backend.
The tests decide, not vibes
Your code runs against real xUnit test suites on .NET. Pass/fail is deterministic — the AI never grades you.
It adapts to you
Struggle on a concept and the game diagnoses why and builds targeted practice. Already know LINQ? It moves you up instead of making you sit through it.
Ship real backends
Capstones like an auth-enabled notes API and the LaunchBoard game backend, with a senior-engineer code review — the answer to tutorial hell. Ship a portfolio, not just streaks.
Your first passing .NET test is minutes away.
Start the C# track — freeFree tier is genuinely free — every banked exercise is playable. We gate AI help and fresh generation, never the content.