How to set up .NET analytics

Feb 11, 2025

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.NET is one of the most powerful and diverse programming platforms. It used to build web apps, microservices, mobile apps, and even games.

No matter what you are building, you’ll want to track how people are using it and find areas to improve. PostHog and its suite of tools like product analytics work perfectly for this.

In this tutorial, we show you how to create a basic .NET web API, add PostHog, and capture data into PostHog.

Creating our .NET web API

After ensuring you have the .NET SDK installed, create a new Web API named PostHogTutorial:

Terminal
dotnet new webapi -o PostHogTutorial

We’ll modify the basic app by adding an email parameter to the get weatherforecast request. This helps us showcase the features of PostHog better.

To do this, go to Program.cs and add the email parameter as well as a check for the email. Your modified code should look like this:

C#
// Program.cs
// ... existing code


var summaries = new[]
{
    "Freezing", "Bracing", "Chilly", "Cool", "Mild", "Warm", "Balmy", "Hot", "Sweltering", "Scorching"
};


app.MapGet("/weatherforecast", (string? email) =>
{
    if (string.IsNullOrEmpty(email))
    {
        return Results.BadRequest("Please include an email parameter in your request");
    }


    var forecast = Enumerable.Range(1, 5).Select(index =>
        new WeatherForecast
        (
            DateOnly.FromDateTime(DateTime.Now.AddDays(index)),
            Random.Shared.Next(-20, 55),
            summaries[Random.Shared.Next(summaries.Length)]
        ))
        .ToArray();
    return Results.Ok(forecast);
})
.WithName("GetWeatherForecast");


// ... existing code

Once you’re ready, run dotnet build and then dotnet run and then go to http://localhost:<port>/weatherforecast?email=your@email.com to see your app in action (the port is randomly assigned).

App is running

Adding PostHog to our .NET app

Now that we have a basic app up and running, we can set up PostHog. Start by installing the PostHog .NET SDK:

Terminal
dotnet add package PostHog.AspNetCore --prerelease

Next, update your appsettings.json to include your project API key and host, both of which you can get from your project settings:

JSON
{
  "Logging": {
    "LogLevel": {
      "Default": "Information",
      "Microsoft.AspNetCore": "Warning"
    }
  },
  "AllowedHosts": "*",
  "PostHog": {
    "ProjectApiKey": "<ph_project_api_key>",
    "Host": "https://us.i.posthog.com"
  }
}

Now, PostHog is ready to use in your app.

Capturing an event with PostHog

With PostHog installed and ready to go, we just need to go to Program.cs to set up an event capture.

In Program.cs, register the PostHog service to your app, inject PostHog into the route handler, and then use it to capture a forecasted weather event when someone makes a weather forecast request. We’ll also use $set to set the person property with the on the person. This makes it easier to filter for events based on email later.

Altogether, this looks like this:

C#
// Program.cs
using PostHog;


var builder = WebApplication.CreateBuilder(args);


builder.Services.AddOpenApi();
builder.AddPostHog();


var app = builder.Build();


if (app.Environment.IsDevelopment())
{
    app.MapOpenApi();
}


app.UseHttpsRedirection();


var summaries = new[]
{
    "Freezing", "Bracing", "Chilly", "Cool", "Mild", "Warm", "Balmy", "Hot", "Sweltering", "Scorching"
};


app.MapGet("/weatherforecast", (string? email, IPostHogClient postHogClient) =>
{
    if (string.IsNullOrEmpty(email))
    {
        return Results.BadRequest("Please include an email parameter in your request");
    }


    var forecast = Enumerable.Range(1, 5).Select(index =>
        new WeatherForecast
        (
            DateOnly.FromDateTime(DateTime.Now.AddDays(index)),
            Random.Shared.Next(-20, 55),
            summaries[Random.Shared.Next(summaries.Length)]
        ))
        .ToArray();


    postHogClient.Capture(
        distinctId: email,
        eventName: "forecasted weather",
        properties: new Dictionary<string, object>
        {
            ["$set"] = new Dictionary<string, object>
            {
                ["email"] = email
            }
        });


    return Results.Ok(forecast);
})
.WithName("GetWeatherForecast");


// ... rest of your code

Now, run dotnet build and dotnet run again and head to http://localhost:<port>/weatherforecast?email=your@email.com. After a few moments, you’ll see a forecasted weather event captured in PostHog.

PostHog

From here, you can set up other features like group analytics, feature flags, or experiments.

Questions? Ask Max AI.

It's easier than reading through 592 docs articles.

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