When loading a question, I noticed calls to clc.stackoverflow.com. Upon loading the subdomain's landing page, I only get this uninformative message:

Oh, hi. I didn't see you there.

SE's CDN has a thorough explanation on it:

This is a fast, cookieless domain intended for static content delivered to the Stack Exchange family of websites [...]

For what is clc.stackoverflow.com used? And can the default page provide a better explanation similar the the cdn url?

  • 15
    Oh no, you found it .... :(
    – rene
    Nov 24, 2014 at 19:29
  • One loaded resource: http://clc.stackoverflow.com/j/p?d=hireme
    – Mooseman
    Nov 24, 2014 at 19:34
  • It has something to do with careers...
    – nicael
    Nov 24, 2014 at 19:36

2 Answers 2


(A little late, I know... but better late than never!)

I'm on the team responsible for the clc.stackoverflow.com domain/app.

Jason's answer is essentially correct. That domain is used for our in-house ad server, which currently serves these things:

enter image description here

Originally, those job ads were served by the Careers application. We decided in late 2013 to split the serving of those listings off into its own project with a dedicated team, so that we could do cool things like use Providence to show our users jobs that are better suited to their interests. We wanted to be able to explore and test different strategies without being tied to the development cycle of either the Core Q&A or Careers teams.

So, why the domain? Early on we went with a Futurama theme for the project (our team chat room is called Planet Express), and the name of the web application that lives at that domain is Calculon:

From our internal Gitlab server

clc was chosen as the domain prefix simply because it's a 3-letter mnemonic for "Calculon". It doesn't actually stand for anything.

We're planning on putting some information up on the homepage explaining what the domain is used for and other informative things. We just haven't gotten to it yet.

Hope that clears some things up!

  • 8
    What? No! Don't take Steve (the other Steve) away! May 19, 2016 at 20:53
  • 3
    I'm thinking about incorporating it into the new page somehow (don't worry, I'm rather fond of Steve-not-that-steve-the-other-steve myself).
    – rossipedia
    May 19, 2016 at 21:32
  • 3
    CLC = Calculon Likes Cats
    – Adam Lear StaffMod
    May 21, 2016 at 3:45
  • 2
    I am considering blocking clc.stackoverflow.com now :F Seriously it is hindering my moderation because all the javascripts including "show more comments" are blocked until the stuff has been downloaded. Nov 15, 2017 at 18:18
  • that's.... not good and is a bug if that's indeed the case. what browser are you using?
    – rossipedia
    Nov 15, 2017 at 18:20
  • Firefox 56.0 64-bit, Ubuntu 17.10. It has been for a while... several browser versions I guess. Now again, I clicked on Add comment... here and was instead sent to the document top, (i.e. href="#"), with status indicator saying the all-too-common message ~*Transferring data from clc.stackoverflow.com*. Nov 15, 2017 at 18:27
  • I will look into that, thank you. We should definitely not be blocking anything else on the page
    – rossipedia
    Nov 15, 2017 at 18:35
  • It seems that for as long as some of the sidebars are loading, the close, add a comment etc "links" won't have their click handlers bound. Nov 15, 2017 at 23:00

It serves content for the careers ads on the right.

I don't see any requests to that host with AdBlock enabled. With it disabled, I see a request, to which the response is some JavaScript that generates the careers blurb.

  • 1
    I'm accepting this answer as it answers my question. I would, however, still like to see SE staff add a better explanation.
    – Mooseman
    Nov 25, 2014 at 11:41

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