Firefox Developer Mac

Firefox Developer Tools is a set of web developer tools built into Firefox. You can use them to examine, edit, and debug HTML, CSS, and JavaScript.

Firefox regular on the left, Firefox Developer on the right. When you install Firefox Developer, you don’t have to worry about it affecting the setup you currently have with regular Firefox; you can install both applications side by side and they will function independently. This is due to Firefox setting up different user profiles for each. Select 'Debugger' from the Web Developer submenu in the Firefox Menu (or Tools menu if you display the menu bar or are on Mac OS X) Press Ctrl + Shift + Z on Windows and Linux, or Cmd + Opt + Z on macOS (starting in Firefox 71; prior to Firefox 66, the letter in this shortcut was S). Press the menu button , select 'Developer', then 'Debugger'.

This section contains detailed guides to all of the tools as well as information on how to debug Firefox for Android, how to extend DevTools, and how to debug the browser as a whole.

The Inspect Element developer tool in Firefox allows you pinpoint the HTML code for anything you see on your web page. The HTML and accompanying CSS stylesheet are fully editable once these tools are open. Experiment with any changes you. Oct 07, 2020 Download Mozilla Firefox Developer Edition for Mac to get the latest features, fast performance, and the development tools you need to build for the open web. Mozilla Firefox Developer Edition has.

If you have any feedback on DevTools or want to contribute to the project, you can join the DevTools community.

Note: If you are just getting started with web development and using developer tools, our learning docs will help you — see Getting started with the Web and What are browser developer tools? for good starting points.

The Core Tools

You can open the Firefox Developer Tools from the menu by selecting Tools > Web Developer > Toggle Tools or use the keyboard shortcut Ctrl + Shift + I or F12 on Windows and Linux, or Cmd + Opt + I on macOS.

The ellipsis menu on the right-hand side of Developer Tools contains several commands that let you perform actions or change tool settings.

This button only appears when there are multiple iframes on a page. Click it to display a list of the iframes on the current page and select the one with which you want to work.

Click this button to take a screenshot of the current page. (Note: This feature is not turned on by default and must be enabled in settings before the icon will appear.)

Toggles Responsive Design Mode.

Opens the menu that includes docking options, the ability to show or hide the split console, and Developer Tools settings. The menu also includes links to the documentation for Firefox Web Tools and the Mozilla Community.

Closes the Developer Tools

Page Inspector

View and edit page content and layout. Visualize many aspects of the page including the box model, animations, and grid layouts.

Web Console

See messages logged by a web page and interact with the page using JavaScript.

JavaScript Debugger

Stop, step through, examine, and modify the JavaScript running on a page.

Network Monitor

See the network requests made when a page is loaded.

Performance Tools

Analyze your site's general responsiveness, JavaScript, and layout performance.

Responsive Design Mode

See how your website or app will look and behave on different devices and network types.

Accessibility inspector

Provides a means to access the page's accessibility tree, allowing you to check what's missing or otherwise needs attention.

Application panel

Provides tools for inspecting and debugging modern web apps (also known as Progressive Web Apps). This includes inspection of service workers and web app manifests.

Note: The collective term for the UI inside which the DevTools all live is the Toolbox.

More Tools

These developer tools are also built into Firefox. Unlike the 'Core Tools' above, you might not use them every day.

Memory: Figure out which objects are keeping memory in use.
Storage Inspector: Inspect cookies, local storage, indexedDB, and session storage present in a page.
DOM Property Viewer: Inspect the page's DOM properties, functions, etc.
Eyedropper: Select a color from the page.
Style Editor: View and edit CSS styles for the current page.
Taking screenshots: Take a screenshot of the entire page or of a single element.
Measure a portion of the page: Measure a specific area of a web page.
Rulers: Overlay horizontal and vertical rulers on a web page

For the latest developer tools and features, try Firefox Developer Edition.

Connecting the Developer Tools

If you open the developer tools using keyboard shortcuts or the equivalent menu items, they'll target the document hosted by the currently active tab. But you can attach the tools to a variety of other targets, too, both within the current browser and in different browsers or even different devices.

about:debugging: Debug add-ons, content tabs, and workers running in the browser.
Connecting to Firefox for Android: Connect the developer tools to an instance of Firefox running on an Android device.
Connecting to iframes: Connect the developer tools to a specific iframe in the current page.
Connecting to other browsers: Connect the developer tools to Chrome on Android and Safari on iOS.

Debugging the browser

By default, the developer tools are attached to a web page or web app. But you can also connect them to the browser as a whole. This is useful for browser and add-on development.

Browser Console: See messages logged by the browser itself and by add-ons, and run JavaScript code in the browser's scope.
Browser Toolbox: Attach the Developer Tools to the browser itself.

Firefox Developer Edition

Extending DevTools

For information on extending the Firefox DevTools, see Extending the developer tools over in the Browser Extensions section of MDN.

Migrating from Firebug

Uninstall Firefox Developer Edition Mac

Firebug has come to the end of its lifespan (see Firebug lives on in Firefox DevTools for details of why), and we appreciate that some people will find migrating to another less familiar set of DevTools to be challenging. To ease a transition from Firebug to the Firefox developer tools, we have written a handy guide — Migrating from Firebug.

Contribute

If you want to help improve the developer tools, these resources will get you started.

Get Involved: Our community website explains how to get involved.
bugs.firefox-dev.tools: A tool helping to find bugs to work on.

Firefox Developer Portable

The Mozilla Foundation has an alternative to its stable client where they publish test versions of its browser that will be officially distributed in the future. Firefox Developer Edition has now replaced the Aurora channel to offer an updated version of the browser each month and a half, long before its launch on the standard channel, and also has some extra functionalities focused on web development.
This version includes several tools to create, edit, and test projects on several devices and browsers, with all the new features grouped into a drop-down menu in the toolbar. It includes the WebID system, a development kit to create webpages and applications for Firefox OS, and also has an extension to view and edit projects on other devices like smartphones and tablets, and another to check pages on other browsers like Chrome or Safari.
Its other features include options to inspect the page's source code and modify the HTML and CSS directly from the browser while viewing the changes in real time. It also offers debugging and performance-analysis options that allow, for example, checking the status of the network when sending online requests, or viewing a change log with all the interactions you do to a page.
For the standard user, the only difference from the original Firefox is a darker theme and the aforementioned features that aren't yet included on the stable channel, making this version ideal for developers as well as those who want to be privy to the latest developments on their favorite browser.