Sometimes you need to encode a string  with a base64 encoding. For example when trying to send a HTTP request with a Basic Authentication header like that:

### own  controller:
POST http://thedomain.com/webhook/post?XDEBUG_SESSION_START=11931
Content-Type: application/json
Authorization: Basic c25zOlVzZVRoZWZvcmNlCg==
{
  "uuid": "08e9a8d3-9279-4af5-88ff-ebe42359f0e0",
  "eventname": "peng.page.publish",
  "data": {
    "sitemap_id": "1234",
    "locale": "de_DE",
    "path": "unigue/page/path",
    "title": "Testpage over API",
    "meta_title": "string",
    "meta_keywords": "string",
    "meta_description": "string",
    "content": "<p >This is a nice dummy storypage with widget marker.</p><p>{{widget type=\"Magento\\Catalog\\Block\\Product\\Widget\\Link\" anchor_text=\"TESTPRODUKT\" title=\"TESTPRODUKT\" template=\"product/widget/link/link_inline.phtml\" id_path=\"product/1\"}}</p>",
    "active": true,
    "css": "",
    "js": ""
  }
}

###

As you can see the Basic Auth username and password are included in the request as a base64 encoded string.

On the Linux shell this string can be generated by the following command:

$> echo "USERNAME:PASSWURD" | base64

Im my blog post  Protect directory with username and password I show how to generate the password hash for Basic Auth via .htaccess file itself.