How to change base url of Swagger in ASP.NET core

You can do this as well in Config

app.UseSwaggerUI(c =>
            {
                c.RoutePrefix = string.Empty;
                c.SwaggerEndpoint("/swagger/v1/swagger.json", "MY API");
            });

The new swagger version provides you with a property called RoutePrefix.

app.UseSwaggerUI(c =>
{
    c.SwaggerEndpoint("/swagger/v1/swagger.json", "My API V1");
    c.RoutePrefix = "docs";
});

Should work for .net core

For ASP.NET Core 2 (and using Swashbuckle.AspNetCore.Swagger -Version 4.0.1), a couple things can be done for a full configuration of changing the default swagger UI base URL.

If you want to add "mycoolapi" to the beginning of your default swagger UI URL, like this: http://<server>/mycoolapi/swagger, then do the following:

In your Startup.cs Configure method:

    app.UseSwagger(c =>
    {
        c.RouteTemplate = "mycoolapi/swagger/{documentname}/swagger.json";
    });


    app.UseSwaggerUI(c =>
    {
        c.SwaggerEndpoint("/mycoolapi/swagger/v1/swagger.json", "My Cool API V1");
        c.RoutePrefix = "mycoolapi/swagger";
    });

Then, if you currently have your launchSettings to launch browser at swagger UI upon startup (for development purposes), update your launchSettings.json file profiles section similarly:

  "profiles": {
    "IIS Express": {
      "commandName": "IISExpress",
      "launchBrowser": true,
      "launchUrl": "mycoolapi/swagger",
      "environmentVariables": {
        "ASPNETCORE_ENVIRONMENT": "Development"
      }
    },
    "MyProject.Web": {
      "commandName": "Project",
      "launchBrowser": true,
      "launchUrl": "mycoolapi/swagger",
      "applicationUrl": "https://localhost:5001;http://localhost:5000",
      "environmentVariables": {
        "ASPNETCORE_ENVIRONMENT": "Development"
      }
    }
  }