Basic Authentication on IIS Express

Update ApplicationHost.config

In the the ApplicationHost.config file, find the following nodes and update the values:

<sectionGroup name="authentication">
   <basicAuthentication enabled="false" /> <!-- set to false -->
</sectionGroup>

<!-- ... -->

<authentication>
   <section name="basicAuthentication" overrideModeDefault="Allow" /> <!-- set to allow -->
</authentication>

Locate ApplicationHost.config

• VS 2015 and above (per Joost's answer):

  sln_folder/.vs/applicationhost.config
  

• VS 2013 and below:

  %UserProfile%\Documents\IISExpress\config\applicationhost.config
  

  As far as I know, there is no way to enable it for only one project.

An additional heads up, in Visual Studio 2015, the location of the applicationhost.config file that is actually being used is inside a folder called .vs inside your solution folder. The one in your user profile is not being used

Here are slightly more details than the previous answer had:

1. %USERPROFILE%\Documents\IISExpress\config\applicationhost.config: <basicAuthentication enabled="true" />

2. In the same file: set <anonymousAuthentication enabled="false" userName="" />

3. If you are not using domain test accounts, create a local user account with the password for the test login.