Content negotiation: List of default Accept values

Default values

These are the values sent when the context doesn't give better information. Note that all browsers add the */* MIME Type to cover all cases. This is typically used for requests initiated via the address bar of a browser, or via an HTML <a> element.

User Agent	Value	Comment
Firefox	text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8	This value can be modified using the network.http.accept.default parameter.
Safari, Chrome	application/xml,application/xhtml+xml,text/html;q=0.9, text/plain;q=0.8,image/png,*/*;q=0.5	source
Safari 5	text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8	This is an improvement over earlier Accept headers as it no longer ranks image/png above text/html
Internet Explorer 8	image/jpeg, application/x-ms-application, image/gif, application/xaml+xml, image/pjpeg, application/x-ms-xbap, application/x-shockwave-flash, application/msword, */*	See IE and the Accept Header (IEInternals' MSDN blog).
Edge	*/*
Opera	text/html, application/xml;q=0.9, application/xhtml+xml, image/png, image/webp, image/jpeg, image/gif, image/x-xbitmap, */*;q=0.1

Values for an image

When requesting an image, like through an HTML <img> element, user-agent often sets a specific list of media types to be welcomed.

User Agent	Value	Comment
Firefox	*/* (since Firefox 47) image/png,image/*;q=0.8,*/*;q=0.5 (before)	This value can be modified using the image.http.accept parameter.
Safari	*/*
Chrome	image/webp,image/*,*/*;q=0.8	Was */* before the support for webp
Internet Explorer 8 or earlier	*/*	See IE and the Accept Header (IEInternals' MSDN blog)
Internet Explorer 9	image/png,image/svg+xml,image/*;q=0.8, */*;q=0.5	See Fiddler is better with Internet Explorer 9 (IEInternals' MSDN blog)

Values for a video

When a video is requested, via the <video> HTML element, most browsers use specific values.

User Agent	Value	Comment
Firefox earlier than 3.6	no support for <video>
Firefox 3.6 and later	audio/webm, audio/ogg, audio/wav, audio/*;q=0.9, application/ogg;q=0.7, video/*;q=0.6; */*;q=0.5	See bug 489071
Chrome	*/*
Internet Explorer 8 or earlier	no support for <video>

Values for audio resources

When an audio file is requested, like via the <audio> HTML element, most browsers use specific values.

User Agent	Value	Comment
Firefox 3.6 and later	audio/webm,audio/ogg,audio/wav,audio/*;q=0.9,application/ogg;q=0.7,video/*;q=0.6,*/*;q=0.5	See bug 489071
Safari, Chrome	?
Internet Explorer 8 or earlier	no support for <audio>
Internet Explorer 9	?

Values for scripts

When a script is requested, like via the <script> HTML element, some browsers use specific values.

User Agent	Value	Comment
Firefox	*/*	See bug 170789
Safari, Chrome	*/*
Internet Explorer 8 or earlier	*/*	See IE and the Accept Header (IEInternals' MSDN blog)
Internet Explorer 9	application/javascript, */*;q=0.8	See Fiddler is better with Internet Explorer 9 (IEInternals' MSDN blog)

Values for a CSS stylesheet

When a CSS stylesheet is requested, via the <link rel="stylesheet"> HTML element, most browsers use specific values.

User Agent	Value	Comment
Firefox 4	text/css,*/*;q=0.1	See bug 170789
Safari 5	text/css,*/*;q=0.1
Internet Explorer 8 or earlier	*/*	See IE and the Accept Header (IEInternals' MSDN blog)
Internet Explorer 9	text/css	See Fiddler is better with Internet Explorer 9 (IEInternals' MSDN blog)
Chrome 12	text/css,*/*;q=0.1
Opera 11.10	text/html, application/xml;q=0.9, application/xhtml+xml, image/png, image/webp, image/jpeg, image/gif, image/x-xbitmap, */*;q=0.1
Konqueror 4.6	text/css,*/*;q=0.1