Backend Development

Top Things to Know for C# .NET Backend Development

nemostorm•January 11, 2026•18 min read

Top Things to Know for C# .NET Backend Development

Introduction

Building robust backend applications with C# and .NET requires understanding both the fundamentals and advanced concepts. This comprehensive guide covers the most important things every .NET backend developer should know, from basic architecture principles to advanced performance optimization techniques.

1. Dependency Injection (DI) - The Foundation

Why It Matters

Dependency Injection is the backbone of modern .NET applications. Without proper DI, your code becomes tightly coupled, difficult to test, and hard to maintain.

Key Concepts

Constructor Injection: The most common and recommended approach
Service Lifetime Management: Transient, Scoped, and Singleton services
Service Registration: How and where to register your services

Best Practices

// Good: Constructor injection with interface
public class UserService : IUserService
{
    private readonly IUserRepository _userRepository;
    private readonly ILogger _logger;
    public UserService(IUserRepository userRepository, ILogger logger)
    {
        _userRepository = userRepository;
        _logger = logger;
    }
}// Program.cs or Startup.cs
builder.Services.AddScoped();
builder.Services.AddScoped();

2. Asynchronous Programming - Async/Await

The Async/Await Pattern

Asynchronous programming is crucial for scalable backend applications. It prevents thread blocking and improves application responsiveness.

Common Pitfalls to Avoid

Async Void: Never use async void in backend code
Blocking Calls: Avoid .Result and .Wait() on async operations
Deadlocks: ConfigureAwait(false) for library code

Best Practices

// Good: Proper async/await usage
public async Task GetUserByIdAsync(int id)
{
    var user = await _userRepository.GetByIdAsync(id);
    await _logger.LogInformationAsync($"Retrieved user {user.Name}");
    return user;
}// Bad: Blocking async calls
public User GetUserById(int id)
{
    var user = _userRepository.GetByIdAsync(id).Result; // Blocks thread!
    return user;
}

3. Entity Framework Core - ORM Mastery

Configuration Best Practices

DbContext Lifetime: Use scoped lifetime for DbContext
Connection Resiliency: Implement retry logic for transient failures
Query Optimization: Use AsNoTracking() for read-only queries

Performance Tips

// Efficient querying
public async Task> GetActiveUsersAsync()
{
    return await _context.Users
        .AsNoTracking() // No change tracking needed
        .Where(u => u.IsActive)
        .OrderBy(u => u.LastLoginDate)
        .ToListAsync();
}// Batch operations
public async Task UpdateUserStatusesAsync(List userIds, bool isActive)
{
    await _context.Users
        .Where(u => userIds.Contains(u.Id))
        .ExecuteUpdateAsync(u => u.SetProperty(x => x.IsActive, isActive));
}

4. Exception Handling and Logging

Global Exception Handling

Implement proper exception handling middleware to catch unhandled exceptions and return appropriate HTTP responses.

Structured Logging

// Structured logging with Serilog
public async Task CreateUser(CreateUserRequest request)
{
    _logger.LogInformation("Creating user with email {Email}", request.Email);
    try
    {
        var user = new User { Email = request.Email, Name = request.Name };
        await _userRepository.AddAsync(user);
        await _unitOfWork.SaveChangesAsync();        _logger.LogInformation("User created successfully with ID {UserId}", user.Id);
        return CreatedAtAction(nameof(GetUser), new { id = user.Id }, user);
    }
    catch (DbUpdateException ex)
    {
        _logger.LogError(ex, "Failed to create user with email {Email}", request.Email);
        return BadRequest("Unable to create user. Please try again.");
    }
}

5. API Design and RESTful Principles

RESTful Resource Naming

Use nouns, not verbs: `/api/users` not `/api/getUsers`
Use HTTP methods correctly: GET, POST, PUT, DELETE
Use plural nouns for collections

Versioning Strategies

URL versioning: `/api/v1/users`
Header versioning: `Accept: application/vnd.api.v1+json`
Query parameter: `/api/users?version=1`

Response Consistency

// Consistent API responses
public class ApiResponse
{
    public bool Success { get; set; }
    public string Message { get; set; }
    public T Data { get; set; }
    public List Errors { get; set; }
}// Usage in controllers
[HttpGet("{id}")]
public async Task GetUser(int id)
{
    var user = await _userService.GetUserByIdAsync(id);
    return Ok(new ApiResponse
    {
        Success = true,
        Data = user,
        Message = "User retrieved successfully"
    });
}

6. Security Best Practices

Authentication and Authorization

JWT Tokens: Stateless authentication for APIs
Role-based Authorization: [Authorize(Roles = "Admin")]
Policy-based Authorization: Flexible permission systems

Input Validation and Sanitization

// Model validation
public class CreateUserRequest
{
    [Required]
    [EmailAddress]
    [MaxLength(256)]
    public string Email { get; set; }
    [Required]
    [MinLength(2)]
    [MaxLength(100)]
    public string Name { get; set; }
}
// Controller validation
[HttpPost]
public async Task CreateUser([FromBody] CreateUserRequest request)
{
    if (!ModelState.IsValid)
        return BadRequest(ModelState);    // Process request...
}

7. Caching Strategies

Types of Caching

In-Memory Caching: Fast, but lost on app restart
Distributed Caching: Redis, SQL Server cache
Response Caching: HTTP caching headers

Implementation

// Distributed caching with Redis
public async Task GetUserCachedAsync(int id)
{
    var cacheKey = $"user:{id}";
    var user = await _cache.GetStringAsync(cacheKey);
    if (user != null)
    {
        return JsonSerializer.Deserialize(user);
    }
    var userFromDb = await _userRepository.GetByIdAsync(id);
    await _cache.SetStringAsync(cacheKey, JsonSerializer.Serialize(userFromDb),
        new DistributedCacheEntryOptions
        {
            AbsoluteExpirationRelativeToNow = TimeSpan.FromMinutes(10)
        });    return userFromDb;
}

8. Performance Optimization

Database Optimization

Indexing: Proper indexes on frequently queried columns
Pagination: Never return all records at once
N+1 Query Problem: Use Include() or Select() to avoid it

Memory Management

Object Pooling: Reuse expensive objects
Garbage Collection Awareness: Minimize allocations in hot paths
Async Streams: For large data processing

9. Testing Strategies

Unit Testing

// Testing with xUnit and Moq
public class UserServiceTests
{
    [Fact]
    public async Task CreateUser_ValidRequest_ReturnsUser()
    {
        // Arrange
        var mockRepo = new Mock();
        var mockLogger = new Mock>();
        var service = new UserService(mockRepo.Object, mockLogger.Object);
        var request = new CreateUserRequest { Email = "test@example.com", Name = "Test User" };
        // Act
        var result = await service.CreateUserAsync(request);        // Assert
        Assert.NotNull(result);
        Assert.Equal(request.Email, result.Email);
        mockRepo.Verify(r => r.AddAsync(It.IsAny()), Times.Once);
    }
}

Integration Testing

Test your entire application stack, including database interactions and external services.

10. Deployment and DevOps

Containerization

Dockerfile for .NET API FROM mcr.microsoft.com/dotnet/aspnet:8.0 AS base WORKDIR /app EXPOSE 80 FROM mcr.microsoft.com/dotnet/sdk:8.0 AS build WORKDIR /src COPY ["MyApi/MyApi.csproj", "MyApi/"] RUN dotnet restore "MyApi/MyApi.csproj" COPY . . WORKDIR "/src/MyApi" RUN dotnet build "MyApi.csproj" -c Release -o /app/build FROM build AS publish RUN dotnet publish "MyApi.csproj" -c Release -o /app/publish

FROM base AS final WORKDIR /app COPY --from=publish /app/publish . ENTRYPOINT ["dotnet", "MyApi.dll"]

CI/CD Considerations

Automated Testing: Run tests on every push
Code Quality Gates: SonarQube, CodeCov integration
Blue-Green Deployments: Zero-downtime deployments
Health Checks: Proper application monitoring

Conclusion

Mastering these concepts will make you a proficient .NET backend developer. Focus on writing clean, testable, and maintainable code while understanding the underlying principles of scalable application design.

Remember: The best code is not necessarily the most complex, but the most readable and maintainable. Keep learning, stay curious, and always strive to improve your craft.

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