diff --git a/docs/configuration/auth.md b/docs/configuration/auth.md
index 46ff9f6..5638ed1 100644
--- a/docs/configuration/auth.md
+++ b/docs/configuration/auth.md
@@ -58,6 +58,12 @@ At the end, open `configuration.php` and update AuthInterface handler to reflect
         ],
 ```
 
+## Custom Authentication using 3rd party
+
+If you want to use FileGator as a part of another application, you probably already have users stored somewhere else. What you need in this case is to build a new custom Auth adapter that matches the (AuthInterface)[https://github.com/filegator/filegator/blob/master/backend/Services/Auth/AuthInterface.php] to connect those two. Basically, this new adapter will try to authenticate users in your application and store a (User)[https://github.com/filegator/filegator/blob/master/backend/Services/Auth/User.php] object into the filegator's session.
+
+Please look at this simplest (demo auth adapter)[https://github.com/filegator/demo_auth_adapter] to see how all this works.
+
 
 ## API authentication