: Earliest browsers that support if-modified-since or if-none-match headers Based on my observations, google and probably many others are in love with websites that include the Etag and Last-modified

@Ogunnowo487

I read elsewhere that google chrome browser ignores cache-control sent by the server and uses a value of zero.


Citation please? The only reference I found of this is a SO question (June 2012) that states that Chrome will override Cache-Control if the user specifically refreshes the page - which is understandable.

This would also be strange since Google recommends Cache-Control headers in its developer guidelines. Cache-Control is the "newer standard" (although still quite old) and should take priority over other headers if present.


what are the first browsers and versions that support Etag, Last-modified, If-modified-since and If-none-match headers?


With regards to ETag / If-None_match, this question on SO (June 2011) states:


all browsers in popular use, IE5.5+, Safari, Chrome, Opera, and Firefox, all support the ETag/If-None-Match headers.


...but it will no doubt predate this list. (ETags were part of the original HTTP/1.1 spec formerly introduced in 1997.)

Last-modified / If-Modified-Since will certainly predate ETags. I would think the very early browsers would have supported these. This represents the basic fundamentals of any caching mechanism.

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