Basic Authentication it’s often used as a simple security measure or as a temporary authentication method while developing with certain APIs.

While the WordPress HTTP API doesn’t have explicit support for basic authentication, it’s still possible to use it as a header:

$request = wp_remote_post(
  $remote_api_endpoint,
  array(
    'body'    => array( 'foo' => 'bar' ),
    'headers' => array(
      'Authorization' => 'Basic '. base64_encode( $username .':'. $password )
    )
  )
);

Remember that if you’re sending an unencrypted request, all the headers will be sent in plain text, so you should only use it over HTTPS.