Firefox is a popular web browser that comes pre-installed on many computers. It’s easy to use and has a lot of features, but one of its hidden gems is the built-in PDF reader. If you’re not familiar with PDFs, they are a type of document that can be read onscreen or printed. They are often used to store documents such as contracts or financial reports. To use the PDF reader in Firefox, first open the browser and click on the three lines in the top right corner (known as the “hamburger menu”). From here, select “Tools” and then “Options.” In the “General” tab, click on the “PDF Reader” button. Next, you’ll need to decide whether you want to use Firefox’s built-in viewer or install a third-party plugin. The built-in viewer is free and works well enough for most purposes, but if you need more features or prefer an alternative viewer then you can install a plugin. There are many good plugins available online so it’s worth checking out some of them before making your decision. Once you’ve made your choice, click on the “Add” button and select your preferred PDF reader from the list that appears. Firefox will now start using this reader whenever you open a PDF file. ..

Note: obviously if you need to access more advanced PDF features, you’ll still need the Adobe plugin. For most of us, however, the built-in viewer is fine, or you could download PDF files and read them in the offline Adobe Reader.

Enabling Firefox’s Built-in PDF Reader

Open Firefox and navigate to about:config.

This will bring up a sarcastic warning telling you that you might void your warranty, just click the “I’ll be careful, I promise!” button to move on.

Now you will need to search for:

When you find it, right click on it and select Toggle from the context menu.

Next you will need enable the actual PDF Reader feature, you can do this by searching for:

That’s all there is to it, you can even drag PDF files on your local machine on t0 the Firefox windows to view them!

Note: As pointed out in the comments, you will need to disable the Adobe addon after you have completed this.