---
title: .NET Client SDK
description: Statsig's SDK for Experimentation and Feature Flags in .NET applications.
product: general
token_estimate: 1764
---
# .NET Client SDK

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- **Repository:** [dotnet-sdk](https://github.com/statsig-io/dotnet-sdk)

## Set up the SDK

1. **Install the SDK**

   [Nuget](https://www.nuget.org/packages/Statsig/) hosts the package. Install it from your Visual Studio's Nuget package manager, or through the NuGet CLI:

   ```shell
   nuget install Statsig
   ```
2. **Initialize the SDK**

   Next, initialize the SDK with a client SDK key from the ["API Keys" tab on the Statsig console](https://console.statsig.com/api_keys). These keys are safe to embed in a client application.

   Along with the key, pass in a [User Object](#statsig-user) with the attributes you'd like to target later in a gate or experiment.

   ```csharp
   using Statsig;
   using Statsig.Client;

   await StatsigClient.Initialize(
       "client-sdk-key",
       new StatsigUser { UserID = "some_user_id", Email = "user@email.com" },
       new StatsigOptions(new StatsigEnvironment(EnvironmentTier.Development)) // optional, use when needed to customize certain behaviors
   );
   ```

## Use the SDK

### Checking a Feature Flag/Gate

Now that your SDK is initialized, check a [**Feature Gate**](https://docs.statsig.com/feature-flags/overview). Feature Gates create logic branches in code that you can roll out to different users from the Statsig Console. Gates are always **CLOSED** or **OFF** (equivalent to `return false;`) by default.

```csharp
if (StatsigClient.CheckGate("new_homepage_design"))
{
  // Gate is on, show new home page
}
else
{
  // Gate is off, show old home page
}
```

### Reading a Dynamic Config

Feature Gates are useful for simple on/off switches with optional advanced user targeting. To send a different set of values (strings, numbers, and so on) to clients based on specific user attributes such as country, use **Dynamic Configs**. The API is similar to Feature Gates, but you get a complete JSON object you can configure on the server. You can then fetch typed parameters from it. For example:

```csharp
DynamicConfig config = StatsigClient.GetConfig("awesome_product_details");

// The 2nd parameter is the default value to be used in case the given parameter name does not exist on
// the Dynamic Config object. This can happen when there is a typo, or when the user is offline and the
// value has not been cached on the client.
string itemName = config.Get<string>("product_name", "Awesome Product v1");
double price = config.Get<double>("price", 10.0);
bool shouldDiscount = config.Get<bool>("discount", false);
```

### Getting a Layer/Experiment

**Layers/Experiments** let you run A/B/n experiments. Statsig offers two APIs, but recommends [layers](https://docs.statsig.com/experiments/layers-overview) to enable quicker iterations with parameter reuse.

```csharp
// Values via getLayer

Layer layer = StatsigClient.GetLayer("user_promo_experiments");
var promoTitle = layer.Get("title", "Welcome to Statsig!");
var discount = layer.Get("discount", 0.1);

// or, via getExperiment

DynamicConfig  titleExperiment = StatsigClient.GetExperiment("new_user_promo_title");
DynamicConfig  priceExperiment = StatsigClient.GetExperiment("new_user_promo_price");

var promoTitle = titleExperiment.Get("title", "Welcome to Statsig!");
var discount = priceExperiment.Get("discount", 0.1);

...

double price = msrp * (1 - discount);
```

### Logging an event

After setting up a Feature Gate or Experiment, you may want to track custom events to see how new features or experiment groups affect those events. Call the Log Event API for the event. You can also provide a value and metadata object to log with the event:

```csharp
StatsigClient.LogEvent(
    "add_to_cart",
    "SKU_12345",
    new Dictionary<string, string>() {
        { "price", "9.99" },
        { "item_name", "diet_coke_48_pack" }
    }
);
```

## Statsig user

You need to provide a StatsigUser object to check/get your configurations. Pass as much information as possible to take advantage of advanced gate and config conditions.

Most of the time, you need the `userID` field to provide a consistent experience for a given user (refer to [logged-out experiments](https://docs.statsig.com/guides/first-device-level-experiment) to understand how to correctly run experiments for logged-out users).

Besides `userID`, Statsig also supports `email`, `ip`, `userAgent`, `country`, `locale` and `appVersion` as top-level fields on StatsigUser. In addition, you can pass any key-value pairs in an object/dictionary to the `custom` field and create targeting based on them.

After the user logs in or their attributes change, call `updateUser` with the updated `userID` and any other updated user attributes:

```csharp
// if you want to update the existing user, or change to a different user, call updateUser

await StatsigClient.UpdateUser(
    new StatsigUser { UserID = "new_user_id", Email = "new_user@email.com" },
);
```

### Private attributes

To prevent logging sensitive user PII, use the `privateAttributes` field on the StatsigUser object. Statsig uses attributes set in `privateAttributes` only for evaluation and targeting, then removes them from any logs before sending them to the server.

For example, suppose you have feature gates that pass only for users with emails ending in "@statsig.com", but you don't want to log your users' email addresses to Statsig. In that case, add the key-value pair `{ email: "my_user@statsig.com" }` to `privateAttributes` on the user.

## Statsig options

`Initialize()` takes an optional parameter `options` in addition to `sdkKey` and `user` that you can provide to customize the Statsig client.

| Name | Type | Required | Default | Description |
| --- | --- | --- | --- | --- |
| environment | StatsigEnvironment | No | — | Set environment variables that apply to all users in the session for targeting purposes. Commonly used to set the environment tier, for example `new StatsigEnvironment(EnvironmentTier.Staging)`. |

| Name | Type | Required | Default | Description |
| --- | --- | --- | --- | --- |
| ClientRequestTimeoutMs | int | No | — | Maximum milliseconds to wait for `/initialize` before proceeding with cached/default values. |

| Name | Type | Required | Default | Description |
| --- | --- | --- | --- | --- |
| PersistentStorageFolder | string | No | — | Directory path for persistent storage of cached values and logs. |

## Shutting Statsig down

The SDK keeps event logs in the client cache and flushes them periodically to save data and battery usage. Because of this periodic flushing, the SDK may not have flushed some events when your app shuts down.

To ensure the SDK flushes or saves all logged events locally, shut down Statsig when your app is closing:

```csharp
StatsigClient.Shutdown();
```

## FAQs

#### How do I run experiments for logged out users

Refer to [Device-level experiments](https://docs.statsig.com/sdks/user#device-level-experiments).