Exploring the Microsoft Feature Management Library in .NET

Exploring the Microsoft Feature Management Library in .NET


In the fast-paced world of software development, the ability to control and manage features dynamically is crucial. The Microsoft Feature Management library, a part of the .NET ecosystem, provides an effective way to add feature flags to .NET applications.

This article explores the key concepts, uses, and advantages of the Microsoft Feature Management library.

What is the Microsoft Feature Management Library?

The Microsoft Feature Management library is a lightweight, extensible library designed to introduce feature flags into .NET applications.

Feature flags, also known as feature toggles, enable developers to turn features on or off dynamically, without deploying new code. This approach offers flexibility in how features are rolled out, tested, and maintained.

Key Features

  • Dynamic Feature Toggling: Change the behavior of your application without needing to redeploy.
  • Percentage-Based Rollout: Gradually roll out features by enabling them for a percentage of users.
  • Integration with Configuration Providers: Works with various configuration providers like Azure App Configuration, environment variables, or any custom provider.
  • Support for .NET Core and .NET Standard: Compatible with modern .NET applications.

How to Use the Feature Management Library

Installation: First, add the Microsoft Feature Management library to your project via NuGet.

dotnet add package Microsoft.FeatureManagement


Define your feature flags in your appsettings.json or any other configuration source.




Service Registration: In your Startup.cs (or program configuration in .NET 5+), register the Feature Management services.

public void ConfigureServices(IServiceCollection services

Usage in Code:

Use the IFeatureManager interface to check if a feature is enabled.

public class MyService 

    private readonly IFeatureManager _featureManager
    public MyService(IFeatureManager featureManager
        _featureManager = featureManager;            

    public async Task DoSomething() 

        if (await _featureManager.IsEnabledAsync("BetaFeature")) 
            // Run beta feature 

ASP.NET Core Integration:

For web applications, you can use feature flags in middleware, MVC, and Razor Pages.

app.UseEndpoints(endpoints => {         

Advanced Scenarios

  • Custom Feature Filters: Implement custom feature filters based on business logic, user identity, or external data.
  • Feature Management UI: Build or integrate a UI for managing feature flags, especially useful for non-technical stakeholders.


  • Agile Deployment: Test and roll out features independently of the deployment cycle.
  • Risk Mitigation: Gradually introduce changes and easily roll them back if needed.
  • Experimentation: Facilitate A/B testing and experimentation without impacting all users.


The Microsoft Feature Management library is a powerful tool for adding flexibility and control to .NET applications.

By employing feature flags, developers can dynamically manage features, enabling more agile deployment strategies, experimentation, and risk mitigation.

As the library integrates seamlessly with the .NET ecosystem and supports custom extensions, it becomes an invaluable asset for modern .NET development practices.


Hi, my name is Stephen Finchett. I have been a software engineer for over 30 years and worked on complex, business critical, multi-user systems for all of my career. For the last 15 years, I have been concentrating on web based solutions using the Microsoft Stack including ASP.Net, C#, TypeScript, SQL Server and running everything at scale within Kubernetes.