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Roadmap

Senior .NET Developer

From C# basics to the architecture of large systems. Every lesson is simple, with pictures and live examples.

58 of 58 lessons readyInterview questions (41)Practice exam
Must know You will not get hired without it.Good to know An extra plus.Specialist Only for special roles.
1

C# and .NET basics

Things we use in code every day and must know deeply.

Must knowModern C#Records, pattern matching, nullable types and new language featuresReadyMust knowasync/await and the thread poolHow Task works and why we must not blockReadyMust knowDependency InjectionService lifetimes and common mistakesReadyMust knowMemory and the Garbage CollectorStack and heap, GC generations, memory leaksReadyMust knowLINQ and collectionsIEnumerable or IQueryable, choosing the right collectionReadyGood to knowPerformance and SpanFewer allocations, BenchmarkDotNet, hot pathsReady
2

ASP.NET Core

Building correct, safe and reliable APIs.

Must knowMiddleware and the pipelineThe path of a request from start to endReadyMust knowAuthentication and authorizationJWT, OAuth2, OpenID Connect and policiesReadyMust knowBackground servicesBackground work, scopes and graceful shutdownReadyGood to knowMinimal APIs and controllersWhich one to use whereReadyGood to knowRate limitingLimiting requests on one or many serversReadyGood to knowgRPC and SignalRFast service-to-service calls and live updates to usersReady
3

Data and storage

Store data correctly, read it fast, and control concurrency.

Must knowEntity Framework CoreTracking, N+1, migrations and performanceReadyMust knowSQL and indexesQuery plans, the right index, paging on big tablesReadyMust knowTransactions and isolation levelsLost updates, deadlocks and locksReadyMust knowRedisData structures, cluster, distributed locksReadyMust knowCaching patternsCache-aside, cache invalidation, stampedeReadySpecialistNoSQLMongoDB and when to use it instead of SQLReady
4

Code design

Write code the team can read and change for years.

Must knowClean CodeGood names, small functions, readable codeReadyMust knowSOLIDFive basic object-oriented design rules, with examplesReadyMust knowDesign patternsStrategy, Decorator, Factory, Mediator and moreReadyMust knowClean ArchitectureOnion layers and the direction of dependenciesReadyGood to knowDomain-Driven DesignShared language, Bounded Context, AggregateReadyGood to knowCQRS and MediatorSeparating reads and writes, the MediatR libraryReadyGood to knowVertical SliceOrganizing code by featureReady
5

Testing

Change code without fear, because tests are watching.

Must knowUnit tests with xUnitWhat a good test looks like, mocks and fakesReadyMust knowIntegration testsTestcontainers and WebApplicationFactoryReadyGood to knowTDDTest first, then code: red, green, refactorReadySpecialistBDDTests in business language with Given, When, ThenReady
6

Distributed systems

When the system is spread over many servers and databases.

Must knowMicroservicesService boundaries, data per service, costsReadyMust knowOutbox and InboxSending messages safely together with database changesReadyMust knowIdempotencyOne request, any number of times, one resultReadyMust knowResilience with PollyRetry, circuit breaker, timeout and retry stormsReadyGood to knowThe Saga patternTransactions across services with compensationReadyGood to knowConsistency and CAPEventual consistency and hard choicesReadySpecialistEvent SourcingStoring events instead of the final stateReady
7

Messaging

Services talk with messages, not only with direct calls.

Must knowKafkaTopics, partitions, consumer groups and message orderReadyGood to knowRabbitMQExchanges, queues and routing patternsReadyGood to knowMassTransitSimple messaging in .NET, saga state machinesReadyGood to knowSchema evolutionChanging message shape without breaking consumersReady
8

Actor model

Another model for concurrency. Each actor has its own state and message queue.

SpecialistActor modelThe main idea and why locks are not neededReadySpecialistMicrosoft OrleansGrains, silos, virtual actors and deadlocksReadySpecialistAkka.NETClassic actors compared with OrleansReady
9

Observability

Know exactly what is happening in production.

Must knowStructured loggingSerilog, log levels, correlation IDsReadyMust knowDistributed tracingOpenTelemetry, traces and spans across servicesReadyGood to knowMetrics and alertsPrometheus, Grafana and good alertsReady
10

Infrastructure and DevOps

Ship code to production safely and repeatably.

Must knowDockerSmall images, multi-stage builds, layersReadyGood to knowKubernetesPods, deployments, HPA and graceful shutdownReadyGood to knowCI/CDPipelines, automated tests, safe deploysReadySpecialistAPI gateway with YARPOne entry point for all servicesReady
11

Architecture and system design

The big decisions. How to build a system that can grow.

Must knowArchitecture stylesMonolith, modular monolith, microservices, event-drivenReadyMust knowSystem designHorizontal scaling, load balancing, sharding, replicasReadyMust knowSecurityOWASP Top 10, secret management, encryptionReadyGood to knowArchitecture Decision RecordsWriting down architecture decisions and their reasonsReady
12

Senior skills

A senior does not only write code. They also help the team and the product grow.

Must knowCode reviewWhat to look for and how to give feedbackReadyGood to knowTechnical debtFinding, measuring and reducing technical debtReadyGood to knowMentoringHelping team members growReadyGood to knowEstimation and planningEstimating work, splitting big tasks, riskReady