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How to open certain mime type in Firefox browser


How can I make Firefox open a certain mime type file in Firefox itself and not start a new Firefox or save it to disk? The mime type is just an ascii file (text/x-dods_das actually), but in Firefox I can only select "Save" "Always ask" or an external program. I want Firefox to just display the file.

Additional System Details

Installed Plug-ins

  • -Office Plugin for Netscape Navigator
  • Adobe PDF Plug-In For Firefox and Netscape
  • NPRuntime Script Plug-in Library for Java(TM) Deploy
  • Default Plug-in
  • Google Update
  • Shockwave Flash 10.1 r53
  • GEPlugin
  • 4.0.50524.0
  • Virtual Earth 3D 4.00090316005 plugin for Mozilla
  • Java(TM) Platform SE binary
  • Next Generation Java Plug-in 1.6.0_17 for Mozilla browsers
  • DRM Netscape Network Object
  • DRM Store Netscape Plugin
  • Npdsplay dll


  • User Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-GB; rv: Gecko/20100722 Firefox/3.6.8 ( .NET CLR 3.5.30729)

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Helpful Reply

You can try using the MIME Edit extension to add that MIME Type to Firefox.

MIME-Edit for Firefox 3.0 - 3.6a1pre http://space.geocities.yahoo.co.jp/gl/alice0775/view/20080912/1221150790 Make sure you grab the version labeled Firefox: 3.0.* ~ 3.7.*

Screenshot of the MIME Edit Options windows: http://space.geocities.jp/alice0775/_gl_images_/MimeEdit.jpg

Question owner

With the MIME Edit extension I can make Firefox start e.g. Notepad to display the file. If the same type of file is opened in Firefox without a mime type being present (in the HTTP header I suppose), Firefox displays the file in a browser window (as if it were a html file without DOCTYPE and tags, see screen-shot). With the MIME Edit it still is not possible to specify this behaviour, which would for me be the most desirable option.

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If the server sends the file as text/plain then Firefox will open that file in a browser tab. Tools > Page Info > General : Content-Type: text/plain; charset=UTF-8


You can use Alt + left-click to open the download dialog (Open with)


harrison3001 0 solutions 1 answers

Fantastic!! I have been able to set automatic download for msi installers without prompt with the mime- type extension by the link you provided. Yuo saved my day!! Many thanks. Andrea.

Mime Edit Extension (Thanks)



  • 対応バージョン:Firefox: 3.0.* ~ 3.7.*

Modified by harrison3001

andresuppsala 0 solutions 1 answers

Thank you for the info!

ZillaChilla 0 solutions 7 answers

The site: http://space.geocities.yahoo.co.jp/gl/alice0775/view/20080912/1221150790 is completely down, or at least I cannot access it.

I have FF 3.5 and would love to get hold of the MIME Edit add-on somehow.

The-Edmeister have you still got a copy of the one for FF 3.0.* + 3.7.* ?? If so could you or anyone else that still has a copy upload it to a bitlocker and send the link here?

I would also like to try this out on the latest FF 4 but am not sure if alice0775 did have one up for that version. If he/she indeed had an MIME edit FF add-on for 4.* would you The-Edmeister or anyone else that has this great add-on upload it to a bitlocker and post the link here as well?

That would be tremendously appreciated. Unfortunately the site seems to have gone off-line completely just recently and this MIME edit add-on for FF seems a real hard to find gem.

Thanks for any help towards this. Tried editing the .rdf file manually but not sure what to write exactly. Any ways, thanks for any help.

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Sorry, I haven't needed that extension in many years and don't have it saved on this PC. For some reason, WhiteAlice0775 never placed that extension on the AMO website - https://addons.mozilla.org/en-US/firefox/user/84420/

AFAIK it has only been available from that Geocities - Yahoo webspace, which was shutdown by Yahoo in 10/2009.  Apparently, the Yahoo Japan Geocities web site lasted a bit longer than the USA version did - http://en.wikipedia.org/wiki/GeoCities
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She seems to have moved to GitHub.

ZillaChilla 0 solutions 7 answers

Thanks Ed and Cor for your replies.

Do you think she can be contacted over GitHub? Is the MIME Edit online somewhere there and possibly it has to be compiled? No idea.

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It seems that she only moved over to GitHub about a week ago, so it is possible that she only moved the most recent files to GitHub so far and more will follow later. She is usually around on the mozillaZine forum site, so you can give it a try there.