(This question is not about nofollow, which is something different.)

I've noticed that all external links are marked with the noreferrer attribute. The only discussions I can find of this on meta.SO and meta.SE are:

However, I don't see any explicit statement that either of these were the actual reason for adding the attribute. Or was there another reason?

Removing referrer information does have a downside. By preventing website owners from discovering what questions they are linked from, we lose the opportunity of them visiting the question and contributing their expertise.

1 Answer 1


I hate to tell you this, but referrer has never been a consistent source of information.

  1. SO/SE is now fully served over HTTPS. So if you run a HTTP site, you'll get no referrer data from any browser, period (per IETF standards)
  2. Many browser add-ons and even browsers themselves (in private modes) will hide the data
  3. Other reasons listed in $_SERVER['HTTP_REFERER'] missing

The chat thing was about plugging the JS opener security hole. Firefox didn't properly support noopener at the time. But you can't rely on it being there.

  • 2
    Thanks, I'm aware of that. But if the referrer is potentially useful both to the target site and to the SE site, shouldn't it be changed to noopener once that's widely enough supported? (The Firefox Bugzilla link says they supported it 16 months ago, but I appreciate that may not be enough time for everyone to upgrade.)
    – mhsmith
    Feb 16, 2018 at 15:29
  • This answer doesn't address the question as to why the attribute is applied. Jun 27 at 21:48

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