Use the Page Inspector to examine and modify the HTML and CSS of a page.

You can examine pages loaded in the local copy of Firefox or in a remote target such as Firefox for Android. See remote debugging to learn how to connect the developer tools to a remote target.

User Interface Tour

To find your way around the Inspector, here's a quick tour of the UI.

From Firefox 62 onwards, you can split the Rules view out into its own pane, separate from the other tabs on the CSS pane — this is called 3-pane mode.

How to

To find out what you can do with the Inspector, see the following how to guides: