How to Customize Firefox with about:config

While Firefox is my favorite web browser, the default interface has become more annoying over the past couple of years due to copying features from Safari and Google Chrome. Here are some quick tips for getting the best features from the older interface back.

Update for 2015

There’s an easier way to add these customizations all at once. Create a file called user.js and put it in your Firefox profile folder. (See how to find your Firefox profile folder.) Paste the following code into the file and restart Firefox:

Please see also the relevant Code Self Study wiki page.

How to Start

Type about:config in the address bar to bring up the advanced options. Click the image below for a quick animated demonstration:

Firefox about:config
Firefox about:config

Fix the Trimmed URLs

Google Chrome and some other browsers started trimming URLs in the address bar. That means that the displayed URL is not the actual URL. For example, the URL, will be displayed as, without the HTTP protocol or trailing slash.

The trailing slash is part of the URL. Hiding these things will just make the public stupider about technology over time. The concepts are not difficult and there is no reason to hide the true URLs.

Search about:config for browser.urlbar.trimURLs and double click it to set it to false.

Protect Your Privacy

Search about:config for privacy.trackingprotection.enabled and double click it so that it says true. (See also: Protect Your Online Privacy with Firefox Browser.)

Stop the URL from Auto-filling

Google Chrome’s interface is annoying because the behavior is inconsistent. The fastest way to use a computer is with muscle memory, and inconsistent behavior in an interface is an obstacle to developing and using muscle memory. When the URL bar autofills, the behavior is inconsistent and it actually makes things slower.

Google Chrome does this in a way that encourages the users to land on Google search results rather than the site they are looking for, while Firefox doesn’t slow things down in that way. You can guarantee the same behavior every time by stopping the suggestions from popping into the address bar and using the TAB key to choose the desired result instead.

To fix this, set browser.urlbar.autoFill to false.

How to Search in a Background Tab

Power users don’t need to wait for pages to load. When I open a new tab, I generally want it to load in the background by default. I time the opening of new tabs so that I don’t have to watch pages load. Watching pages load in the foreground is a waste of time.

To search Google, you can highlight some text on a webpage, right-click, and press the <code>s</code> key. That used to open up the search tabs in the background, which is the way I want it. Firefox recently changed it so that it pops up a new tab on top of what you are looking at. Chrome does it that way and it’s very annoying.

To fix it, double click on to set it to true.

How to Turn Off Browser Tab Animation

If you don’t like animation, set browser.tabs.animate to false.

Stop Auto-select

When you click in the address bar in Windows, the entire URL is automatically selected. If you want to turn off that annoying feature, set
browser.urlbar.clickSelectsAll to false.

Other Tips

Do you have any other tips for using about:config? Post your favorite modifications in the comments below!

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