To see what it's like in earlier versions of Firefox or in Firefox Beta and Release, see Debugger (before Firefox 52).
If you are getting this version of the Debugger and need to switch back to the old version, you can do so by visiting about:config and setting the "devtools.debugger.new-debugger-frontend" preference to
There are three ways to open the debugger:
- 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 the CtrlShiftS (CommandOptionS on OS X) keyboard shortcut
- press the menu button ( ), press "Developer", then select "Debugger".