On the standards track: Yes
Is Experimental: No
Is Deprecated: No
In Chrome version 1 on 2008-12-11
In Chrome Android version 18 on 2012-06-27
In Edge version 12 on 2015-07-29
In Firefox version 1 on 2004-11-09 Note: Starting from Firefox 49, empty headers are returned as empty strings in case the preference network.http.keep_empty_response_headers_as_empty_string is set to true, defaulting to false. Before Firefox 49 empty headers had been ignored. Since Firefox 50 the preference defaults to true.
In Firefox for Android version 4 on 2011-03-29 Note: Starting from Firefox for Android 49, empty headers are returned as empty strings in case the preference network.http.keep_empty_response_headers_as_empty_string is set to true, defaulting to false. Before Firefox for Android 49 empty headers had been ignored. Since Firefox for Android 50 the preference defaults to true.
In Internet Explorer version 5 on 1999-03-18
In Quest Browser version 5.0 on undefined
In Opera version 8 on 2005-04-19
In Opera Android version 10.1 on 2010-11-09
In Safari version 1.2 on 2004-02-02
In Safari on iOS version 1 on 2007-06-29
In Samsung Internet version 1.0 on 2013-04-27
In WebView Android version 4.4 on 2013-12-09
In WebView on iOS version 1 on 2007-06-29