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Revision as of 03:09, 12 April 2012 by Sebastianz (Talk | contribs) (Added detailed description of how the activation model works)

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Activation in Firebug Terminology means enabling its modules, so they start processing the data of a specific website. Firebug supports different activation models. These models were improved over time. The biggest change happened in Firebug 1.4.

Firebug Activation

Per URL (whitelist)

The default behavior is to enable Firebug per URL. This means that if you open Firebug via F12 or by clicking its Start Button being at a website, the next time you visit the same website the Firebug window will be opened again. It thereby follows the same origin policy with the exception that subdomains are not treated differently.


Firebug is activated for When you go to it will be activated as well. Also if you go to the Firebug window will be opened. But if you go to, it won't be activated.

There's a preference Activate Same Origin URLs to control if the activation should follow the same origin policy. If this option is disabled, Firebug will disregard the origin when deciding to activate or not.


Firebug is activated for When you go to it won't be activated as well as when you go to

Always enabled

Firebug will always be activated. This means Firebug will be activated regardless of which page you visit. This behavior can be enabled via Firebug Start Button Menu > On for All Web Pages.

Having this option enabled also hides options to deactivate Firebug.

Panel Activation

Besides the general activation of Firebug there are also some panels, which allow to enable/disable them. The reason for disabling single panels is to avoid wasting system resources for things you don't need. E.g. as a web designer you probably won't need the Net Panel functionality.

The panel activation model currently only supports an on/off state. I.e. if you enable the Script Panel, it will subsequently be enabled for all sites Firebug is activated for.

Currently Firebug has three panels that support activation:

Also there are some extensions, which allow disabling their panels.

See also