Make Firefox Open PDF Instead of Downloading


Are you tired of Firefox automatically downloading every PDF file to your disk without giving you the option to open it directly? You’re not alone. Many users find this default behavior frustrating, but the good news is that there’s a simple solution.

In this article, we’ll guide you through the steps to stop Firefox from automatically downloading PDF files and instead allow you to open them directly.

Understanding Firefox’s Behavior

Firefox determines what a file is, based on the content-type header it receives from the server hosting the file. Another crucial header is the content-disposition header, which is the server’s suggestion in how the browser should handle the file. The two primary options for content-disposition are “inline” and “attachment”:

  • “Inline” is the default behavior, meaning the browser will handle the file according to your browser settings.
  • “Attachment” forces the browser to download the file.

Because of these settings, based on what the remote server instructs, some PDF files may be downloaded automatically, while others are handled according to your browser settings. It’s worth noting that if a server sends the PDF with a header of “attachment”, and Firefox is set to obey it, this is what causes the download of the PDF.

Therefore, the solution is to force the PDF to be opened “inline”.

The Solution

To ensure that Firefox opens PDF files instead of downloading them, follow these simple steps:

1. Open about:config

Type “about:config” in the Firefox address bar and press Enter. Accept the risk and continue to the configuration page.

2. Find the Setting

In the search bar at the top, type “”

3. Change the Preference

Double-click on the “” preference to toggle it from “false” to “true.”

That’s it! You’ve successfully configured Firefox to open PDF files instead of automatically downloading them. From here, if you decide you need the file, you can still download it to a location of your choosing.


By understanding Firefox’s file-handling behavior and making a simple configuration change in the about:config settings, you can take control of how PDF files are handled in your browser. Say goodbye to the frustration of automatic downloads and hello to the convenience of opening PDFs directly. If you’ve ever wondered, “Why is Firefox downloading PDF files?”—now you have the solution.

Remember, this quick guide not only addresses how to stop Firefox from automatically downloading PDF files but also provides insight into the mechanisms behind Firefox’s default behavior. Enjoy a smoother browsing experience by customizing your browser to suit your preferences.

Now you can open PDFs hassle-free and save time by skipping unnecessary downloads.