We have a site, example.com, that includes a login system for the end users.

We then have a CMS, cms.example.com, in which admin users log in to edit the content of the main site.

Both sites are treated as separate projects, with independent login systems and different front ends, because we want to give the users different UXs.

We're considering migrating the CMS to its own domain, something like cmsexample.com.

The reasong behind it is that we think the web is moving towards treating a domain always as a single entity, without distinction of subdomains, for the sake of clarity and transparency towards the end user.


  • Browser behaviour: logging into cms.example.com will trigger the following message on Firefox and IE: "Would you like to store your password for example.com?".
  • Firefox, IE and Opera highlight the domain name on the URLs, ie they consider the subdomain a less important part of the URL: cms.example.com/path/to/file
  • On www.facebook.com, users get seamlessly redirected to apps.facebook.com when using an app.
  • Google takes users from mail.google.com to accounts.google.com for authentication, and then back to mail.google.com once they are logged in.

But there is also a large number of counterexamples, including this very same site ux.stackexchange.com, blogs and personal sites hosted on many blogging platforms, or custom sites like companyname.mainproduct.com.

In a nutshell then, the question is: Do two different login systems on cmsexample.com / example.com provide a better user experience than if they are on cms.example.com / example.com ?

2 Answers 2


clarity and transparency towards the end user

Why would the end user care about if the CMS is on a seperate domain or subdomain? If I would move the CMS of one of my customers to a seperate domain, they won't notice because there's just one thing they want to do: manage their website and nothing else. They won't pay attention to the address bar.

Did you notice the accounts.google.com before you were wondering whether to move the CMS to a seperate domain or not? I would bet that you didn't, because instinctively, you focus on the window with the actual content which can help the user, instead of the address bar. Why would a user pay attention to that?


Do two different login systems on cmsexample.com / example.com provide a better user experience than if they are on cms.example.com / example.com ?



I'm not sure how many administrators you have and what their skill level is, but if they look anything like our customers they will just look for an e-mail with the URL or a bookmark to the CMS and they really don't care what the domain is.

Also, since people don't really read pop-ups, I doubt anybody will notice the missing subdomain in the message. (I for one never noticed it, I know I get the pop-up for password and don't read it. I know instinctively what it's asking me.

Also since I suspect that the CMS is a private site, no content without login, you don't really have to think about SEO or best URL's or anything. Just make the UI great.

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