Note: Although the APIs are based on the Chrome devtools APIs, there are still many features that are not yet implemented in Firefox, and therefore are not documented here. To see which features are currently missing please see Limitations of the devtools APIs.

The devtools.panels API lets a devtools extension define its user interface inside the devtools window.

The devtools window hosts a number of separate tools - the JavaScript Debugger, Network Monitor, and so on. A row of tabs across the top lets the user switch between the different tools. The window hosting each tool's user interface is called a "panel".

With the devtools.panels API you can create new panels in the devtools window.

Like all the devtools APIs, this API is only available to code running in the document defined in the devtools_page manifest.json key, or in other devtools documents created by the extension (such as the panel's own document). See Extending the developer tools for more.



Represents the HTML/CSS inspector in the browser's devtools.


Represents a devtools panel created by the extension.


Represents a pane that an extension has added to the HTML/CSS inspector in the browser's devtools.



A reference to an ElementsPanel object.


The name of the current devtools theme.



Creates a new devtools panel.



Fired when the devtools theme changes.

Example extensions

Browser compatibility

BCD tables only load in the browser

Note: This API is based on Chromium's chrome.devtools.panels API.