How can I get Firefox to display MIME types in-browser?

Question

When I click on a *.json or *.patch file in Firefox, it asks me what external application I want to view it in.

However, I don't want to use an external application. It's plain text -- I just want to view it in-browser.

There doesn't seem to be anything in the UI for this.

Answer 1

Here's an add-on that might help: "Open in browser"

And here's a KB article that also might help, "MimeTypes"

Answer 2

In general you should use the "tools->options->applications" to edit which application is used by default to open different mime types. However if you can't set it that way you can edit the mimeTypes.rdf directly, but this is discouraged.

Adding the following should work (use at your own risk):

<RDF:Description RDF:about="urn:mimetype:application/json"
           NC:value="application/json"
           NC:path="<path to firefox>"
           NC:saveToDisk="false"
           NC:editable="true"
           NC:prettyName="JSON object">
<NC:handlerProp RDF:resource="urn:mimetype:handler:application/json"/>
</RDF:Description>

Answer 3

http://support.mozilla.com/en-US/kb/Managing+file+types

If you open the preferences windows and go to the Applications tab, you should be able to find the content type (application/json) and change its action to "Use Firefox"