Html – Max parallel HTTP connections in a browser


I am creating some suspended connections to an HTTP server (comet, reverse AJAX, etc). It works ok, but I see the browser only allows two suspended connections to a given domain simultaneously. So if a user is looking at my website in Tab1 of their browser, then also tries loading it in Tab2, they've used up the two allowed connections to my site.

I think I can do some wildcard domain thing, where I have my HTTP server resolve any address to my site like:

*  -> (the actual ip of my server)


all still point to ( but the browser considers them different domains, so I don't run into the 2 connection limit. Is this true?

Even if that is true – is there any limit to the number of active connections per browser, across all domains? Say I use the scheme above – does Firefox for example only allow 24 parallel connections at any given time? Something like:

25) // Error - all 24 possible connections currently in use!

I just picked 24 connections/Firefox as an example.

Best Solution

Max Number of default simultaneous persistent connections per server/proxy:

Firefox 2:  2
Firefox 3+: 6
Opera 9.26: 4
Opera 12:   6
Safari 3:   4
Safari 5:   6
IE 7:       2
IE 8:       6
IE 10:      8
Edge:       6
Chrome:     6

The limit is per-server/proxy, so your wildcard scheme will work.

FYI: this is specifically related to HTTP 1.1; other protocols have separate concerns and limitations (i.e., SPDY, TLS, HTTP 2).