Similar extension Rated 2 out of 5 stars

The Open in Browser extension does this and more:

https://addons.mozilla.org/addon/open-in-browser/

InlineDisposition vs. Open in Browser

No, not really. While Open in Browser can ultimately accomplish the same thing, it is fundamentally different from InlineDisposition. Whereas InlineDisposition lets the browser carry on as if the attachment-disposition header was never set, Open in Browser was designed primarily to handle unknown MIME types, and as a *side effect*, it can also force open attachment-disposition content.

First, this means that InlineDisposition works automatically; if the browser supports opening a particular MIME type, it will, without the user having to instruct the browser to do so. With Open in Browser, you have to tell the browser to open the content inline (and what type to open it as) each and every time; for sites that use attachment-disposition extensively (there is a major image host that does this), Open in Browser is completely unsuitable.

Second, there is actually very little overlap between InlineDisposition and Open in Browser. In fact, the two extensions are complementary to each other: InlineDisposition is better suited for handling attachment-disposition issues while Open in Browser handles unknown MIME types. The two extensions can work alongside and in tandem with each other.

Third, because InlineDisposition is very limited and narrow in its scope (it targets attachment-disposition specifically and does not dabble in anything else), it also leaves a much smaller footprint. It is restartless, tiny (just 3KB in size), and works automatically without the need for user action/interaction.