How to Use Dotnet Core Expert in Claude Code - Complete Guide for Beginners

Feb 14, 2026

Purpose

This post demonstrates how to use the Dotnet Core Expert skill in Claude Code for backend development tasks.

When I started using Claude Code, I needed a way to get expert-level .NET Core guidance without switching to separate documentation. The Dotnet Core Expert skill solves this problem by providing specialized knowledge directly within your coding workflow.

Environment

Claude Code with claude-skills plugin
.NET Core 3.1+ / .NET 5+
Beginner to intermediate development experience

What is Dotnet Core Expert?

Dotnet Core Expert is a specialized skill in the claude-skills ecosystem that provides:

Architecture patterns for .NET Core applications
API design best practices (REST, GraphQL)
Entity Framework Core guidance
Dependency injection patterns
Security implementation strategies
Performance optimization techniques

The skill targets developers who want expert-level .NET Core guidance without leaving their development environment.

I think the key benefit is context-aware assistance. Instead of generic answers, you get .NET Core-specific solutions that match your project’s architecture and constraints.

Installation and Setup

First, ensure you have claude-skills installed:

# Navigate to your skills directory
cd ~/.claude/skills

# Clone or download claude-skills
git clone https://github.com/jeffallan/claude-skills.git

The Dotnet Core Expert skill activates automatically when you:

Work in a .NET Core project directory (contain .csproj files)
Use .NET Core-specific keywords in your prompts
Ask about backend architecture, APIs, or Entity Framework

To verify it’s working, try:

Use dotnet-core-expert to design a Web API controller

Core Usage Patterns

Basic Invocation

The skill triggers when you:

Direct invocation (most reliable):
```
Use dotnet-core-expert for [task]
```

Contextual triggers (.NET projects):

How do I implement repository pattern in this .NET Core API?

Keyword-based activation:

Design a .NET Core Web API with Entity Framework

Common Trigger Phrases

- "Use dotnet-core-expert to design..."
- "Create a .NET Core service with..."
- "Implement Entity Core pattern for..."
- "Design authentication for .NET API..."

Practical Examples

Example 1: Web API Controller Design

When I needed to create a new API controller, I used:

Use dotnet-core-expert to design a ProductsController with CRUD operations

The skill provided a complete controller following .NET Core best practices:

[ApiController]
[Route("api/[controller]")]
public class ProductsController : ControllerBase
{
    private readonly IProductService _productService;
    private readonly ILogger<ProductsController> _logger;

    // Constructor injection
    public ProductsController(
        IProductService productService,
        ILogger<ProductsController> logger)
    {
        _productService = productService;
        _logger = logger;
    }

    [HttpGet]
    public async Task<ActionResult<IEnumerable<Product>>> GetAll()
    {
        try
        {
            var products = await _productService.GetAllAsync();
            return Ok(products);
        }
        catch (Exception ex)
        {
            _logger.LogError(ex, "Error retrieving products");
            return StatusCode(500, "An error occurred");
        }
    }

    [HttpGet("{id}")]
    public async Task<ActionResult<Product>> GetById(int id)
    {
        var product = await _productService.GetByIdAsync(id);

        if (product == null)
        {
            return NotFound();
        }

        return Ok(product);
    }
}

The skill explained the key patterns:

Constructor injection for dependencies
Async/await for database operations
Proper HTTP status codes (200, 404, 500)
Error logging with ILogger
RESTful naming conventions

Example 2: Repository Pattern Implementation

I asked:

Use dotnet-core-expert to implement repository pattern with Entity Framework Core

The result included both interface and implementation:

public interface IProductRepository
{
    Task<IEnumerable<Product>> GetAllAsync();
    Task<Product> GetByIdAsync(int id);
    Task<Product> AddAsync(Product product);
    Task UpdateAsync(Product product);
    Task DeleteAsync(int id);
}

public class ProductRepository : IProductRepository
{
    private readonly AppDbContext _context;

    public ProductRepository(AppDbContext context)
    {
        _context = context;
    }

    public async Task<IEnumerable<Product>> GetAllAsync()
    {
        return await _context.Products.ToListAsync();
    }

    public async Task<Product> GetByIdAsync(int id)
    {
        return await _context.Products
            .FirstOrDefaultAsync(p => p.Id == id);
    }

    public async Task<Product> AddAsync(Product product)
    {
        await _context.Products.AddAsync(product);
        await _context.SaveChangesAsync();
        return product;
    }

    public async Task UpdateAsync(Product product)
    {
        _context.Products.Update(product);
        await _context.SaveChangesAsync();
    }

    public async Task DeleteAsync(int id)
    {
        var product = await GetByIdAsync(id);
        if (product != null)
        {
            _context.Products.Remove(product);
            await _context.SaveChangesAsync();
        }
    }
}

The skill explained why this pattern works:

Separates data access from business logic
Makes unit testing easier with mocking
Follows SOLID principles (Dependency Inversion)
Works well with Entity Framework Core’s change tracking

Example 3: Authentication with JWT

I needed JWT authentication for my API:

Use dotnet-core-expert to implement JWT authentication in .NET Core Web API

The skill provided a complete authentication setup:

// Add JWT authentication
builder.Services.AddAuthentication(JwtBearerDefaults.AuthenticationScheme)
    .AddJwtBearer(options =>
    {
        options.TokenValidationParameters = new TokenValidationParameters
        {
            ValidateIssuer = true,
            ValidateAudience = true,
            ValidateLifetime = true,
            ValidateIssuerSigningKey = true,
            ValidIssuer = builder.Configuration["Jwt:Issuer"],
            ValidAudience = builder.Configuration["Jwt:Audience"],
            IssuerSigningKey = new SymmetricSecurityKey(
                Encoding.UTF8.GetBytes(builder.Configuration["Jwt:Key"]))
        };
    });

builder.Services.AddAuthorization();

public class AuthService : IAuthService
{
    private readonly IConfiguration _configuration;

    public AuthService(IConfiguration configuration)
    {
        _configuration = configuration;
    }

    public string GenerateToken(User user)
    {
        var securityKey = new SymmetricSecurityKey(
            Encoding.UTF8.GetBytes(_configuration["Jwt:Key"]));
        var credentials = new SigningCredentials(
            securityKey, SecurityAlgorithms.HmacSha256);

        var claims = new[]
        {
            new Claim(ClaimTypes.NameIdentifier, user.Id.ToString()),
            new Claim(ClaimTypes.Email, user.Email),
            new Claim(ClaimTypes.Role, user.Role)
        };

        var token = new JwtSecurityToken(
            issuer: _configuration["Jwt:Issuer"],
            audience: _configuration["Jwt:Audience"],
            claims: claims,
            expires: DateTime.Now.AddHours(2),
            signingCredentials: credentials);

        return new JwtSecurityTokenHandler().WriteToken(token);
    }
}

The skill highlighted critical security practices:

Store JWT key in user secrets (not hardcoded)
Set reasonable token expiration
Include role claims for authorization
Use HMAC SHA256 for signing
Validate all token parameters

Best Practices

DO ✓

1. Use specific prompts

"Design a .NET Core Web API with repository pattern and EF Core"

2. Provide context

"This is an e-commerce API. Use dotnet-core-expert to design the Order entity"

3. Ask for explanations

"Use dotnet-core-expert and explain why async/await matters here"

4. Request security reviews

"Use dotnet-core-expert to review this controller for security issues"

5. Follow-up with refinement

"Refactor this service to use dependency injection properly"

DON’T ✗

1. Vague requests

"Help with .NET"  // Too broad

2. Ignore .NET Core conventions

Don’t use synchronous database calls
Don’t hardcode connection strings
Don’t skip dependency injection

3. Skip error handling

// WRONG: No error handling
public async Task<Product> GetProduct(int id)
{
    return await _context.Products.FindAsync(id);
}

4. Avoid logging

// WRONG: No logging
public async Task<bool> DeleteProduct(int id)
{
    var product = await _context.Products.FindAsync(id);
    _context.Products.Remove(product);
    await _context.SaveChangesAsync();
    return true;
}

Common Use Cases

1. API Design

Use dotnet-core-expert to design RESTful API endpoints for user management

Provides:

HTTP method mapping (GET, POST, PUT, DELETE)
Route templates
Request/response DTOs
Validation attributes

2. Database Design

Use dotnet-core-expert to design EF Core entities for blog posts

Provides:

Entity classes with proper annotations
DbContext configuration
Relationship mappings (one-to-many, many-to-many)
Index suggestions

3. Performance Optimization

Use dotnet-core-expert to optimize this slow API endpoint

Analyzes:

N+1 query problems
Missing indexes
Synchronous I/O operations
Caching opportunities

4. Security Implementation

Use dotnet-core-expert to add authorization to this controller

Provides:

Role-based authorization
Policy-based authorization
Resource-based authorization
JWT token validation

Dotnet Core Expert works well with:

security-review: For comprehensive security audits
backend-patterns: For general API design patterns
tdd-guide: For test-driven development in .NET Core

Summary

In this post, I showed how to use Dotnet Core Expert skill in Claude Code for backend development. The key point is that this skill provides expert-level .NET Core guidance directly in your development workflow, from API design to security implementation.

The skill helps you write better .NET Core code by:

Following established patterns and conventions
Implementing proper error handling and logging
Using dependency injection correctly
Applying security best practices
Optimizing for performance

Final Words + More Resources

My intention with this article was to help others share my knowledge and experience. If you want to contact me, you can contact by email: Email me

Here are also the most important links from this article along with some further resources that will help you in this scope:

Oh, and if you found these resources useful, don’t forget to support me by starring the repo on GitHub!

How to Use Dotnet Core Expert in Claude Code - Complete Guide for Beginners

Purpose

Environment

What is Dotnet Core Expert?

Installation and Setup

Core Usage Patterns

Basic Invocation

Common Trigger Phrases

Practical Examples

Example 1: Web API Controller Design

Example 2: Repository Pattern Implementation

Example 3: Authentication with JWT

Best Practices

DO ✓

DON’T ✗

Common Use Cases

1. API Design

2. Database Design

3. Performance Optimization

4. Security Implementation

Related Skills

Summary

Final Words + More Resources

Comments