I've found a strange thing: some Stack Exchange sites have their own domain names instead of https://[site name].stackexchange.com. The websites which have their own domain names are:

  1. Stack Overflow
  2. Super User
  3. Ask Ubuntu
  4. Server Fault
  5. MathOverflow
  6. Stack Apps
  7. Seasoned Advice

Are there any parameters for allocating specific URLs to Stack Exchange sites?

  • 35
    Bravo for getting all the site names correct with their spacing! Not many people can do that.
    – TRiG
    Commented Feb 12, 2015 at 15:38
  • Have wondered the same thing for a long time. Periodically I update my password for *.stackexchange.com, and I have my browser memorize the new password. I continue using the usual SE sites. Some months later I will want to post on Super User, realize that I have to go dig up the password or set a new one or whatever shenanigans being on a separate domain entails, and 9 times out of 10 I'll conclude that my question is either 1. not that important, 2. better asked on another site, 3. might be found by researching more, or 4. easier to ask on a (not ideal but) similar enough SE sub-site.
    – Mentalist
    Commented Jun 5, 2023 at 0:36

4 Answers 4


It all started with three websites (created at different times), that are known as the "trilogy websites". These were created before Stack Exchange was official.

Some proposals were given new names once they launched.

Some were seeded from Stack Exchange 1.0 websites.

Some were created (not seeded) from Stack Exchange 1.0 websites.

And a few proposals were seeded from non-Stack Exchange 1.0 websites.

There are also some domains used by Stack Exchange that are not for Q&A websites

  • Stack Apps - This just holds applications that were created for use on Stack Exchange websites. While you can ask questions, the primary focus is on setting up applications.
  • Stack Auth - This domain handles the centralized authentication between all Stack Exchange websites.

The API for getting the aliases was pointed out in chat.

  • I'm sure there was also a discussion at some point about why they wouldn't be (obviously with potential exception) be 're-domaining' any of the existing sites any time soon. Commented Mar 12, 2015 at 15:33
  • 4
    @Pureferret Domain Names: The Wrong Question
    – user259867
    Commented Mar 12, 2015 at 16:09
  • I'm pretty sure PPCG.SE can be accessed through alias by ppcg.lol
    – AAM111
    Commented Sep 13, 2016 at 0:11
  • @OldBunny I'm pretty confident that's not owned by SE Commented Sep 13, 2016 at 0:12
  • What do you mean? It redirects to the real PPCG.SE
    – AAM111
    Commented Sep 13, 2016 at 1:14
  • 6
    @OldBunny2800 the ppcg.lol domain is owned by someone else who has chosen to redirect it to PPCG SE. This answer only includes domains owned and operated by Stack Exchange. Commented Sep 13, 2016 at 19:43
  • hashcode meta post link is 404
    – andrybak
    Commented May 9, 2017 at 11:09
  • What exactly does "seeded from Stack Exchange 1.0" mean? Does it mean it was just a continuation of the old community?
    – Stevoisiak
    Commented May 10, 2017 at 5:26
  • For communities which were "seeded", the existing questions and answers were brought over from the old communities into the newer Stack Exchange 2.0 communities. This distinction is important because not all communities could bring their content over (for various reasons). Commented May 10, 2017 at 7:39
  • Enlightening and a good read from the links above: stackoverflow.blog/2010/10/05/domain-names-the-wrong-question Don’t even think about the domain name!
    – Avatar
    Commented Jul 29, 2018 at 16:36
  • I was just about to ask about why do some sites have full domain names while other have site.stackexchange.com. I would have been downvoted and duplicated. Thank god for searching.
    – Big Joe
    Commented May 31, 2023 at 0:31
  • Stack Overflow, Super User, and Server Fault all predate Stack Exchange, meaning that they were created before the concept of Stack Exchange as network of sites existed; hence all three get to keep their original domain.

  • The reason for Ask Ubuntu is covered in this blog post by Jeff. In short, it's due to a partnership with Canonical Ltd.

  • MathOverflow also predates Stack Exchange as a network and was "assimilated" by Stack Exchange at some point; hence it keeps the domain.

  • Stack Apps is not really a Q&A site, at least not in the same sense as all other Stack Exchange sites, hence it makes sense for it to have a different domain.

  • Just for competeness, what about the others like arqade.com, meta.nothingtoinstall.com (nothingtoinstall.com was retired) and seasonedadvice.com? Why are they special? Commented Feb 12, 2015 at 11:48
  • @GeorgeDuckett Kevin did it now. :) Commented Feb 12, 2015 at 14:03
  • Mi Yodeya (Judaism.SE) started as a StackExchange 1.0 community, and its founder chose to use the URL mi.yodeya.com. Because the community already had and liked the name when it entered the StackExchange 2.0 network, StackExchange decided to make the name part of its brand when it launched out of beta.

Stack Overflow, along with Super User and Server Fault, belong to the Original Trilogy. They don't use stackexchange.com because the Stack Exchange network hadn't been named at that point.

See also What is the Stack Overflow "trilogy"?, and "Trilogy" in the SE Glossary.


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