[manarth]

Currently only supported by Firefox (as of 49.0), according to Mozilla [1].

Interestingly, it's being used by the BBC [2], who have reported a 10.8% reduction in 304 responses as a result [3]. Google have also stated their intention to use it (comment 11 in the same Chromium ticket).

[1] https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Ca...

[2] https://mybbc.files.bbci.co.uk/notification-ui/2.6.8-mvt//sv...

[3] https://bugs.chromium.org/p/chromium/issues/detail?id=611416

[renke1]

Another alternative would be service workers, which are (partially) supported by Chrome and Firefox according to [1]

[1]: http://caniuse.com/#feat=serviceworkers