Dotnet

ASP.NET Core Centralized Security Headers Middleware Guide

October 4, 2025 · 6 min

In modern web development, security isn’t an afterthought; it’s a foundational requirement. One of the most effective and straightforward ways to harden your ASP.NET Core application is by using HTTP security headers. These headers instruct the browser on how to behave, mitigating common attacks like Cross-Site Scripting (XSS), clickjacking, and protocol downgrade attacks.

While you can add these headers in various places, the most robust and maintainable approach is to create a single, centralized middleware. This ensures every response from your application is consistently protected.

In this post, we’ll build a configurable security headers middleware from scratch that manages Content-Security-Policy (CSP), HTTP Strict-Transport-Security (HSTS), and other essential headers.

Why a Centralized Middleware?

You might be tempted to sprinkle Response.Headers.Add(...) in your controllers or use separate app.Use...() calls for each header in Program.cs. However, a centralized approach offers significant advantages:

  • Consistency: Every single endpoint gets the same baseline protection without fail. You eliminate the risk of forgetting to secure a new API or page.
  • Single Point of Configuration: All your security header policies live in one place. Need to tighten your CSP? You only have one file to edit.
  • Maintainability: As security standards evolve, updating your policies is trivial. You don’t have to hunt down configurations scattered across the project. …
...

Read more

Writing a Minimal Custom Middleware in ASP.NET Core

October 1, 2025 · 5 min

ASP.NET Core’s request pipeline is a powerful concept built entirely around middleware. Think of it as an assembly line for your HTTP requests. Each station on the line is a piece of middleware that can inspect, modify, or act upon the request before passing it to the next station.

While ASP.NET Core provides a rich set of built-in middleware for things like routing, authentication, and static files, there will inevitably come a time when you need to create your own. Whether it’s for custom logging, header manipulation, or a unique authentication scheme, writing custom middleware is a fundamental skill.

In this guide, we’ll break down the process into its simplest form, showing you two minimal ways to create and use your own middleware.

Approach 1: The Convention-Based Class

The most common and structured way to create middleware is by defining a class that follows a specific convention. This approach is clean, reusable, and testable.

A middleware class needs two things:

  1. A constructor that accepts a RequestDelegate parameter. This delegate represents the next piece of middleware in the pipeline.
  2. A public method named InvokeAsync (or Invoke) that accepts an HttpContext as its first parameter. This is the method that gets executed.

Let’s create a simple middleware that logs the incoming request path and the outgoing response status code.

Step 1: Create the Middleware Class

Create a new file named SimpleLoggingMiddleware.cs. We’ll use a primary …

...

Read more