Implementing Feature Toggles in .NET Core Using the FeatureToggle Framework

Feature toggles (also known as feature flags) allow developers to decouple feature development from code deployment, enabling rapid releases while selectively hiding unfinished features or exposing them to specific users, dates, or environments.

The tutorial introduces the concept, lists common toggle types (e.g., AlwaysOn, AlwaysOff, SimpleFeatureToggle, RandomFeatureToggle, date‑based toggles), and recommends the open‑source FeatureToggle library by Jason Roberts for .NET platforms.

It demonstrates three practical demos:

Demo 1 shows a RandomFeatureToggle that randomly enables a "WeChat notification" menu item.

Demo 2 uses SimpleFeatureToggle with an appsettings.json configuration to control an "Email notification" feature.

Demo 3 creates a custom SpecificUsersFeatureToggle implementing IFeatureToggle to restrict a "SMS notification" feature to specific users.

Each demo includes code snippets wrapped in tags, such as class definitions, service registrations in Startup.cs, view model updates, and Razor view conditional rendering.

Configuration steps involve adding the FeatureToggle package via NuGet, setting up providers (e.g., AppSettingsProvider), and modifying the Startup class to inject toggle services.

The article concludes that feature toggles facilitate continuous delivery, A/B testing, and targeted rollouts, while also noting the need to apply toggles to business logic, not just UI.