about:config Configuration Editor For Mozilla Firefox


Today browsers provide a lot of features and configurations. Mozilla Firefox provides a lot of configurations that can be edited via the Advanced Preferences screen. Advanced Preferences also called about:config which is used to access Mozilla Firefox configuration screen. By using the about:config address or shortcut we can list, read, change, add, delete different Firefox configurations.

What Is about:config ?

Simply the about:config is a shortcut that provides easy access to the Advanced Preferences. about is a term used to access different features of the Mozilla Firefox.

Open about:config

The most basic and easy way to open Advanced Preferences is using the about:config address in the address bar like below. Mozilla Firefox stores different low level and critical configurations in the about:config. So during the access to the about:config Firefox will show a precaution like below. It will simply say Changing advanced configuration preferences can impact Firefox performance or security. .

about:config
Open about:config

When we click to the Accept the Risk and Continue we will see the Advanced Preferences screen like below. It will simply provide a text box in order to search the configuration features. As there is a lot of different configuration options search inside them will be very helpful.

List All Preferences In about:config

By default, none of the configuration preferences are listed for performance and user experience reasons. Alternatively, we can use the Show All button in order to list all configuration options.

Show All Configuration Preferences

The listed configuration options will be shown like below.

All Configuration Preferences For Mozilla Firefox

Search Preferences In about:config

Let’s start using the about:config in order to search a preference. We will just type some text about the preference option. As an example in order to search and find browser.autofocus configuration we can type “browser” or “autofocus” which will be list related configurations.

Search Preferences In about:config

Change Preferences In about:config

Changing preferences can be different according to the preferred type. Boolean type is used to store information like True and False. Text or number preference will store some alphanumeric characters. In order to change the preference, the right side icon like below can be used.

Change Preferences In about:config

Add Preferences In about:config

Adding preference is a bit different which is related to the search. We will type the new preference name to the preference search box. If there are matched preferences they will be listed and at the bottom of them, the typed preference will be listed with a plus sign like below. We will just select the type of preference where Boolean, Number, and String are our options. In this example, we will create a preference named mybrowser and set type as String.

Add Preferences In about:config

We will be asked for the preference value we will put “Just Test” for this example. The last step is clicking OK or check icon like below.

Add New Preference and Value

Remove/Delete Preferences In about:config

Existing preferences can be easily deleted by using the delete button. We will just navigate to the preference we want to delete. We can list by using the search or listing all preferences. In this example, we will delete the preference named mybrowser like below.

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