Feature Toggle libraries for .NET

9th July 2012

The idea of "Feature Toggles" is described in detail by Martin Fowler.

The idea of “Feature Toggles” is described in detail by Martin Fowler. Essentially these give you the ability to enable/disable parts of your application via configuration.

<appSettings>
    <add key="Feature.Toggle1" value="True"/>
</appSettings>

And then within your code, check the config value to enable the feature:

if (bool.Parse(ConfigurationManager.AppSettings["Feature.Toggle1"]))
{

}

Ideally you’d make that check a bit more robust, but you get the idea!

Alternatively, you might want to use one of these libraries that implement feature toggling. I searched for .NET feature toggle libraries and found these four. Coincidentally they are all hosted on GitHub, and all but nToggle are available as NuGet packages.

NFeature

https://github.com/benaston/NFeature

NFeature requires you to create an enum which defines all the feature toggles. It then generates extension methods such that you can check the config setting for a feature. Features are configured through a custom section in the .config file. Features can optionally be configured to depend on other features, and to have availability times set.

<configSections>
    <section name="features" type="NFeature.Configuration.FeatureConfigurationSection`1[[NFeatureTest2.Feature, NFeatureTest2]], NFeature.Configuration" />
</configSections>

<features>
    <add name="MyFeature" state="Enabled" />
    <add name="MyOtherFeature" state="Previewable" />
    <!-- will only be available to users who meet the feature-preview criteria -->
    <add name="MyOtherOtherFeature" state="Disabled" />
</features>

public enum Feature
{
    MyFeature,
    MyOtherFeature,
    MyOtherOtherFeature,
}

...

if ( Feature.MyFeature.IsAvailable( featureManifest ) )
{
    //do some cool stuff
}

NFeature appears to be actively maintained with recent commits.

FeatureToggle

https://github.com/jason-roberts/FeatureToggle

FeatureToggle provides base classes from which you inherit for each feature toggle you want to implement. These toggles are configured in the <appSettings/> section in the .config file.

<appSettings>
   <add key="FeatureToggle.MyAwesomeFeature" value="false" />
</appSettings>

public class MyAwesomeFeature : SimpleFeatureToggle {}

...

if (!MyAwesomeFeature.FeatureEnabled)
{
   // code to disable stuff (e.g. UI buttons, etc)
}

FeatureToggle also has support for WPF and Windows Phone apps.

It is actively maintained with recent commits.

FeatureSwitcher

https://github.com/mexx/FeatureSwitcher

In FeatureSwitcher, toggles are created by implementing the IFeature interface. You then use the Feature<> generic class to test whether a particular toggle is enabled.

Toggles are configured in the .config file via custom sections.

<configSections>
  <sectionGroup name="featureSwitcher" type="FeatureSwitcher.Configuration.SectionGroup, FeatureSwitcher.Configuration">
    <section name="default" type="FeatureSwitcher.Configuration.DefaultSection, FeatureSwitcher.Configuration"/>
    <section name="features" type="FeatureSwitcher.Configuration.FeaturesSection, FeatureSwitcher.Configuration"/>
  </sectionGroup>
</configSections>
<featureSwitcher>
  <default featuresEnabled="true"/>
  <features>
    <feature name="FeatureSwitcher.Examples.BlueBackground" enabled="true"/>
  </features>
</featureSwitcher>

class BlueBackground : IFeature {}

...

if (Feature<Sample>.Is().Enabled)
{

}

FeatureSwitcher is actively maintained with recent commits.

nToggle

https://github.com/SteveMoyer/nToggle

nToggle uses a custom section in the .config file. The examples given show usage with a WebForms app, though it should work with all kinds of applications.

<configSections>
  <section
    name="nToggle"
    type="nToggle.Configuration.ToggleConfigurationSection"
    allowLocation="true"
    allowDefinition="Everywhere"
    />
</configSections>

<nToggle>
  <toggles>
    <add name="TestFeatureOn" value="True"/>
    <add name="TestFeatureOff" value="False"/>
  </toggles>
</nToggle>

<%@ Register assembly="nToggle" namespace="nToggle" tagprefix="nToggle" %>
<nToggle:WebFeatureToggle ID="FeatureToggle1" EnabledBy="TestFeatureOff" runat="server" >
    <span id="enabledby"> Feature Turned Off</span>
</nToggle:WebFeatureToggle>

protected void Page_Load(object sender, EventArgs e)
{
    WebFeatureToggle1.RunActionWhenEnabled(CodeToRunIfEnabled);
}

protected void CodeToRunIfEnabled()
{
    //your code
}

nToggle has not been updated for 7 months at time of writing.