Can anyone recommend an add-on for Firefox Quantum which will let you resize the browser window to a new size, from a list of sizes which you can define?

Up until now, with Firefox ESR (pre-Quantum), I had been using the very useful Browsizer add-on, but Browsizer is not compatible with Firefox Quantum, and no longer appears to be maintained, unfortunately.


  • Must be able to define an indefinite number of window sizes (at least 8: many of the WebExtension add-ons which I have found so far seem to only allow a maximum of 4 window sizes to be defined)
  • Must let you access the settings for the add-on via its toolbar button (so that you can easily add/remove/edit the list of sizes without having to open the Add-ons Manager)


  • Would be useful to be able to also set a window position for a particular window size setting (but this must be an optional setting, as there are only certain occasions where I do want to both resize and reposition a window)

2 Answers 2


Window Resizer works well (just tested it with Firefox 61) and allows you to define custom layouts with screen position (top, left, width, height). I don't think screen position is optionnal though.

  • Thanks for your suggestion. I did come across that one, but unfortunately the fact that you always have to set the window position as well as the size means that it was not quite what I was looking for.
    – dave559
    Commented Jul 26, 2018 at 10:45

I have done some searching on https://addons.mozilla.org/ (which now seems to return better search results than it used to).

The add-on which appears to best meet my requirements so far seems to be ResizeIT, which allows window positions to be optionally set, as well as window sizes to be defined.

Unfortunately ResizeIT only allows you to define 4 window size options, however, so is not quite ideal for me.

There is also WindowSizer, which allows more than 4 resize options, but does not allow window positions to be (optionally) set. It also has a mildly annoying requirement that you give each defined size a title.

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