There may be cases where your main site is not a vBulletin site and you have a forum section using vBulletin 5. And there may be instances where you would want to re-use the vB5 login page then after a successful login, redirect to the main site.

How would you do that? It's easy.

For example, your main site is and your vB5 forum is
  1. In your main site, you can reference to the vB5 login page inside an iframe or in its own window using the following URL:
    You are passing "url" querystring with a value of Base64 encoded URL which is in our example,
    There are Base64 encoder tools online that you can use to do this. One of them is
  2. Once vB5 authentication is successful, it decodes the url querystring value and redirects to that URL.
Open the link below in Private Mode or Incognito Mode to login to this site (obviously, you need to be a registered user here). Once you successfully logged in, you will be redirected to and not to this site.

That's it. Enjoy!