Last week I had to investigate an issue in an old webservice that was still using basic authentication(on a not enforced HTTPS connection ). With basic authentication you have to send a Base64 encoded version of your username/password combination to the server(that explains immediatelly why using basic authentication over a HTTP connection is never a good idea). 
I had to the test the service but the only tool I had available on the server was Fiddler.
So let’s start by creating the Base64 encoded version of our message:
- Open Fiddler
 - Go to Tools –> TextWizard…
 - Type your username password combination separated by a ‘:’, e.g. username:password
 - Choose ToBase64 from the Transform list
 - Copy the generated string
 
Next step is to create our request:
- Go to the Composer tab
 - Type “Authorization: Basic’’after the User-Agent string and add the generated string to the end. The result should look like this:
 
Authorization: Basic dXNlcm5hbWU6cGFzc3dvcmQ=