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Anyone have an idea where can I look up that information? I'm pretty sure that IE 4 has the "Use HTTP 1.1" parameter on by default and the "Use HTTP 1.1 through proxy connections" off. Got this information from here. I assume the later versions would have "Use HTTP 1.1" on too. How about older versions of IE? How about Firefox, Opera, Safari etc?

Svet
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2 Answers2

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All common desktop browsers (Netscape/Mozilla, Internet Explorer, et al) in the last 10-13 years support HTTP/1.1. Internet Explorer 3.0 and Netscape 2.0 supported it as far back as at least 1996 (Wikipedia agrees with this).

Of particular note is that HTTP/1.1 is required for the HTTP HOST header, which is required if you want to serve different websites for different domains on a single IP address. As such if an HTTP client didn't support it, the user would be unable to access many websites.

I encountered an old smartphone browser that didn't support it about 9 years ago, but that's the last example I can think of where I'd even heard of an HTTP client that didn't.

I'd say that lack of client support for HTTP/1.1 does not need to be a real consideration today even if your doing something fairly esoteric (although I still remember it being a technical support headache over 10 years ago, trying to get people to upgrade from Netscape 1.x).

If you are writing a proxy you might want to think about it, but really even then I can't see it causing any real world problems as it's so fundamental to modern browsing. If someone is are running a browser as old (or as limited) as Mosaic 1.0 or Netscape 1.1 then they probably have bigger problems accessing content.

Iain Collins
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  • +1 for mentioning the Host header. As every single website on shared hosting (which must be the majority of sites in the world) is inaccessible to an HTTP/1.0 client, a browser that didn't support 1.1 would be basically unusable. – NickFitz Oct 20 '09 at 16:24
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    @NickFitz not strictly true, `Host` was a non-standard addition to 1.0 before it became part of 1.1. Despite what Wikipedia may say, the first 1.1 RFC was published in 97 (2068 since obsoleted by 2616), but NN2 and IE3 did already have the Host header. – Jon Hanna Aug 27 '12 at 21:20
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Most modern web browsers (at least IE since version 5, Firefox since version 2) don't even have an option to use anything but HTTP/1.1. Well, they might, but it'd be pretty well hidden.

EDIT: found this on Google, which provides partial information: http://schroepl.net/projekte/mod_gzip/browser.htm According to that page, IE4+, Netscape 6+, Opera 4+ and (I gather) all versions of Firefox support HTTP 1.1.

David Z
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