Which browsers support "Cache-control: immutable"?

Asked 30/1, 2017 at 13:10 Answered 25/4, 2019 at 12:54

Solved google-chrome firefox cache-control

I've read that Firefox has begun supporting a cache control extension value of immutable, which means that "the response body will not change over time." So even if a user requests a "full refresh" of a page or resource, the browser still only responds with the locally cached copy, thus avoiding unnecessary 304s or page refreshes, and making pages load faster since cached content is used, and decreasing load on servers, since a large number of requests are stopped before they even happen.

I'm trying to see how well this is supported, and am finding varying answers, as this mozilla page suggests that it's only supported in Firefox, but this resolved Chrome issue suggests it's been available since Chrome v54.

Which browsers support Cache-Control: immutable, and when did they start supporting it?

I first read about it here on this Hacker News discussion

Here's an ietf draft on it, the original mozilla post announcing this beta feature being used by Facebook and this related mozilla post, and a document discussing the different types of reloading requests from some Google chrome devs, it appears.

Cootie answered 30/1, 2017 at 13:10 Comment(0)

As of February 2017, Cache-Control: immutable is supported by

Firefox (https://bugzilla.mozilla.org/show_bug.cgi?id=1267474) since Firefox 49
~~Chrome (https://bugs.chromium.org/p/chromium/issues/detail?id=611416) since Chrome 54~~ They aren't implementing this.
Safari (https://bugs.webkit.org/show_bug.cgi?id=167497) in Safari Technology Preview 24.

It is also listed on MDN and Can I Use ... ?.

Vincenz answered 31/1, 2017 at 12:46 Comment(3)

Chrome does not actually support immutable at the moment, but has its own new heuristics for avoiding lots of conditional requests on a (non-forced) page reload. – Bismarck 9/2, 2017 at 11:47

I'm sure Chrome heuristics made the web faster for majority of its users, but now we have to keep guessing what those heuristics are, be ready for any eventual unannounced changes to those heuristics and we have literally no way to override that behavior when we need to. I'm going to chalk it up as a loss for developers. – Hale 4/12, 2018 at 21:53

FYI bugs.chromium.org/p/chromium/issues/detail?id=611416#c52 reopened the issue. – Lulululuabourg 12/6, 2019 at 13:45

As of April 2017 it is also supported in "classic" Edge

Hypertensive answered 25/4, 2019 at 12:54 Comment(1)

And now Edge is Chromium – Eichelberger 2/3, 2020 at 10:2

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