The browser made for developers

All the latest developer tools in beta, plus experimental features like the Multi-line Console Editor and WebSocket Inspector. A separate profile and path so you can easily run it alongside Release or Beta Firefox. Preferences tailored for web developers: Browser and remote debugging are enabled by default, as are the dark theme and developer toolbar button.

Inactive CSS

Firefox DevTools now grays out CSS declarations that don’t have an effect on the page. When you hover over the info icon, you’ll see a useful message about why the CSS is not being applied, including a hint about how to fix the problem.

Firefox DevTools

The new Firefox DevTools are powerful, flexible, and best of all, hackable. This includes a best-in-class JavaScript debugger, which can target multiple browsers and is built in React and Redux.

Master CSS Grid

Firefox is the only browser with tools built specifically for building and designing with CSS Grid. These tools allow you to visualize the grid, display associated area names, preview transformations on the grid and

Fonts Panel

The new fonts panel in Firefox DevTools gives developers quick access to all of the information they need about the fonts being used in an element. It also includes valuable information such as the font source, weight, style and more.

official mozilla.org/en-US/firefox/developer/


src developer.mozilla.org/en-US/docs/Mozilla/Firefox/Developer_Edition