While the notification about there being new answers to a question you're currently answering has been around for a while, I've noticed more recently Stack Overflow seems to be sending other updates to the client theses days:

  • Indicating new questions since page load when you have a search page open
  • Reputation auto updating
  • Date fields auto updating (created date/ edit date)

So I was wondering technology/framework is Stack Overflow using to push these updates to the client? (Custom AJAX? A JS library?)

I've looked at this question's answer, but I don't see any specific mention.


According to Geoff Dalgas's post here, they're using Web Sockets

Now for the gotchas - in order to use this feature you must have a browser that supports web sockets. See: http://caniuse.com/#search=websockets for a list of browsers that currently support web sockets.

  • 9
    Yep .. no fugly longpoll fallback. I was happy when I read that because it gives me something 'major' to point at where time wasn't wasted on trying to make bonus features work for every browser under the sun.
    – Tim Post
    Apr 17 '12 at 6:39
  • 2
    OMG this doesn't support IE 5.2 for mac? OUTRAGE No seriously good on them for designing for the future/present
    – Ben Brocka
    Apr 21 '12 at 22:05

According to Marc Gravell in Jan 8, 2019,

As of late 2018, Stack Overflow (Stack Exchange) have migrated away from NetGain, instead using Kestrel's inbuilt web-socket support over HTTP/1.*; it is entirely possible that as we delve more into HTTP/2, we look more in the direction of SSE (EventSource).

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .