How does Stack Overflow track or block a user that isn't logged in and that asked or answered a question that has been flagged as spam or offensive? I'm asking because I'm also creating a Q&A site.

  • 5
    If they told you that it wouldn't be very effective, would it?
    – Geobits
    Dec 17, 2013 at 16:54
  • Why do you need to know? Dec 17, 2013 at 16:54
  • 1
    You can't post if you aren't logged in anyway. Or do you want to use a sock puppet?
    – juergen d
    Dec 17, 2013 at 16:54
  • @juergend, not much use for a sock puppet if he cant upvote himself
    – Leeor
    Dec 17, 2013 at 16:55
  • 2
    Time to get down and dirty and learn about web development.
    – Hogan
    Dec 17, 2013 at 16:58
  • @jeurgend Well I can if I'm not logged in
    – C'mon
    Dec 17, 2013 at 16:59
  • @GenericHolidayName Security through obscurity is no security at all Dec 17, 2013 at 17:02
  • @RichardTingle It's poor security, but that's not no security. Some security problems are inherently hard. It's unfortunate to have to rely on obscurity, but sometimes there simply aren't better options available to you. The inherent nature of the web, at some of its most basic levels, prohibit effective identification. Sites are forced to rely on fragile and evadable mechanisms, because they are the only mechanisms available to them.
    – Servy
    Dec 17, 2013 at 17:04
  • @RichardTingle While sometimes true, I don't give out the blueprints to my house to just anyone who might ask for them.
    – Geobits
    Dec 17, 2013 at 17:04
  • What makes you think we block them? Did you see a message recently?
    – user50049
    Dec 17, 2013 at 17:11
  • So... you want SO to provide hidden security information (thus damaging its security posture)... to support the creation of a competing site? Did you really think this through?
    – Ben Barden
    Dec 17, 2013 at 22:25

1 Answer 1


We have several layers of spam protection in place, in key areas of the site where anonymous participation can quickly become a source of frustration if abused.

If you're curious to learn about what we have in place, have a look here, then here, and then explore the linked posts (also in the sidebar).

The short answer, we don't waste an ounce of signal that we get from this sort of activity. We gather it from our users and moderators as they work to keep the site clean, and we gather it from spam networks themselves as they go about their evil deeds. I can't go into very many specifics, but the system is quite simple as far as these sorts of things go, and extremely difficult to defeat.

If you're building a Q&A site, then you first have to make sure you have enough users that care about keeping the place clean, and make sure they have the tools to do it. When a human user that you trust says "this is spam", especially more than one, don't waste that signal.

The mechanics of dealing with it once identified is an exercise to the reader ;)

  • The mechanics of this are undoubtedly fascinating. I'm going back to look at job openings for devs at Stack Exchange... Dec 17, 2013 at 18:44
  • 5
    Details: signal is triple-distilled, bottled in sanitary brown glass and shipped cold to maintain freshness.
    – Shog9
    Dec 17, 2013 at 18:57

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