.NET 10 New Features: What’s New and What Actually Matters​

.NET 10 New Features: What’s New and What Actually Matters​

With .NET 10 officially released, Microsoft continues its steady evolution of the platform with a mix of developer-experience improvements, runtime enhancements, and cloud-native tooling updates. While not every feature will impact all teams equally, several changes in .NET 10 are particularly relevant for modern application development—especially in microservices and production environments.

File-Based Apps​

One of the more developer-friendly additions in .NET 10 is improved support for file-based applications. This approach allows developers to build small applications or services using a single file without the traditional project scaffolding.

From a productivity standpoint, this lowers the barrier for:

1. Prototyping APIs
   
2. Writing internal tools
3. Creating lightweight background jobs

The value here is not about replacing full project structures, but about enabling faster experimentation and clearer examples. File-based apps are particularly useful for proofs of concept, demos, or operational scripts that still benefit from the .NET runtime and ecosystem.

// File: app.cs
#:package Newtonsoft.Json@13.0.4

using Newtonsoft.Json;

var myObject = new { Name = "Cuong Nguyen Duy", Age = 18 };
var json = JsonConvert.SerializeObject(myObject, Formatting.Indented);

Console.WriteLine(json);

Validation in Minimal APIs​

Minimal APIs have been widely adopted for building lightweight services, but validation has historically required additional boilerplate or external libraries. .NET 10 improves validation support directly within Minimal APIs, reducing friction and improving readability.

This enhancement makes Minimal APIs more viable for:

• Internal microservices
• Edge APIs
• High-performance endpoints where minimal overhead matters

From a maintainability perspective, having clearer and more consistent validation behavior reduces the risk of subtle input handling bugs—especially in distributed systems where contracts evolve over time.

Security Improvements​

.NET 10 adds first-class WebAuthn (Passkey) support to ASP.NET Identity, enabling passwordless authentication using public-key cryptography. Passkeys are phishing-resistant by design and eliminate password storage, reuse, and leakage risks.

This implementation is inspired by the widely adopted fido2-net-lib, but is now integrated into the Identity framework with safer defaults and tighter lifecycle management.

New .NET project templates include passkey support by default. Existing ASP.NET Identity applications can add passkeys incrementally, but a database schema migration is required to persist credentials and challenges.

ASP.NET Core Identity Passkey Integration:

builder.Services
    .AddIdentity()
    .AddEntityFrameworkStores()
    .AddDefaultTokenProviders();

builder.Services.Configure(options =>
{
    options.ServerDomain = "auth.yourdomain.com";
});

builder.Services.AddAuthentication("Bearer")
    .AddJwtBearer("Bearer", options =>
    {
        options.Authority = "https://auth.yourdomain.com";
        options.Audience = "your-api";
        options.RequireHttpsMetadata = true;
    });
    

var claims = new[]
{
    new Claim(JwtRegisteredClaimNames.Sub, user.Id),
    new Claim(JwtRegisteredClaimNames.Email, user.Email),
    new Claim("amr", "passkey")
};

var token = new JwtSecurityToken(
    issuer: "https://auth.yourdomain.com",
    audience: "your-api",
    claims: claims,
    expires: DateTime.UtcNow.AddMinutes(30),
    signingCredentials: signingCredentials
);

return Ok(new
{
    access_token = new JwtSecurityTokenHandler().WriteToken(token)
});

/*Controller*/
[Authorize]
[ApiController]
[Route("api/orders")]
public class OrdersController : ControllerBase
{
    [HttpGet]
    public IActionResult GetOrders()
    {
        return Ok();
    }
}

Performance​

Performance remains a central theme in .NET 10. As with recent releases, improvements span the runtime, garbage collection, and JIT compilation.

The most meaningful gains are not about headline benchmarks, but about predictability and efficiency:

• More stable memory usage
• Smoother GC behavior under load
• Faster and more consistent startup times

In containerized environments and high-throughput APIs, these improvements translate into better autoscaling behavior, higher pod density, and lower infrastructure costs. Importantly, many of these benefits can be realized simply by upgrading the runtime, without architectural changes.

Conclusion​

.NET 10 is not defined by a single breakthrough feature. Instead, it delivers a set of focused improvements that enhance productivity, security, and runtime efficiency—particularly for modern, cloud-native workloads.

Enhancements such as file-based apps and improved Minimal API validation streamline developer workflows, while continued runtime and security optimizations provide measurable gains in production environments. Overall, .NET 10 reinforces the platform’s maturity for building and operating distributed systems.

For teams already invested in the .NET ecosystem, the true value of .NET 10 lies not in novelty, but in refinement—and that is what ultimately matters in production.

Referent:
https://learn.microsoft.com/en-us/dotnet/core/whats-new/dotnet-10/overview