.NET – Launch Settings (Basics)

Created2024-10-20Updated2025-10-21

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What is the launchSettings.json file?

  • Location: Properties\launchSettings.json
  • Purpose: defines local run profiles — URLs, HTTPS, environment variables, and startup behavior.
  • Important: used only during local development (dotnet run, Visual Studio); does not affect production.

Key Fields

  • profiles – the collection of profiles (e.g., http, https).
  • commandName – Project → runs the app directly with Kestrel (not IIS Express).
  • applicationUrl – the URLs the app listens to (separated by ;).
  • environmentVariables – environment variables (e.g., ASPNETCORE_ENVIRONMENT).
  • launchBrowser – automatically opens the browser at startup (true/false).
  • dotnetRunMessages – displays active URL messages in the console.

Your Profiles

Example minimal file:

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{
  "profiles": {
    "http": {
      "commandName": "Project",
      "dotnetRunMessages": true,
      "launchBrowser": false,
      "applicationUrl": "http://localhost:5062",
      "environmentVariables": {
        "ASPNETCORE_ENVIRONMENT": "Development"
      }
    },
    "https": {
      "commandName": "Project",
      "dotnetRunMessages": true,
      "launchBrowser": false,
      "applicationUrl": "https://localhost:7165;http://localhost:5062",
      "environmentVariables": {
        "ASPNETCORE_ENVIRONMENT": "Development"
      }
    }
  }
}
  • http – listens only on http://localhost:5062.
  • https – listens on both https://localhost:7165 and http://localhost:5062.
  • If you have app.UseHttpsRedirection() in Program.cs, the http profile will automatically redirect to HTTPS.
    👉 For normal development, use the https profile.

The variable ASPNETCORE_ENVIRONMENT = Development activates conditional blocks such as:

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

How to Run with a Profile

CLI:

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dotnet run --launch-profile https

Visual Studio / Rider / VS Code:
select the desired profile from the run dropdown.

Practical Tips

  • Want local HTTPS? Install the development certificate:
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    dotnet dev-certs https --trust
  • Changing ports? Edit applicationUrl and update your .http or frontend config.
  • You can add custom variables:
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    "environmentVariables": {
      "ASPNETCORE_ENVIRONMENT": "Development",
      "ConnectionStrings__Default": "Host=...;Database=...;"
    }

Summary

  • What it is: a launch profile configuration file used only in development (Properties\launchSettings.json).
  • Used by: dotnet run, Visual Studio, Rider, VS Code.
  • What it configures: URLs (applicationUrl), environment variables (ASPNETCORE_ENVIRONMENT), startup options (launchBrowser).
  • What it doesn’t do: does not affect build/publish and is not used in production.
    For production → use appsettings*.json, environment variables, and host configuration.

In short:
launchSettings.json is a local development tool that defines how your .NET app runs on your machine — not where or how it will run in production.