Enter Checkfox. A Mozilla Firefox add-on that has been designed for users who work regularly with checkboxes. The add-on basically provides the means to check or uncheck multiple checkboxes at once. This is done by selecting the area of the page containing the checkboxes and right-clicking afterwards.

The right-click context menu will display options to check or to uncheck the checkboxes in the selected area. It will only display options to check or to uncheck the boxes if all are unchecked or checked.

Update: The extension will check or uncheck all selected items regardless of their initial state. There is no option to inverse the selection.

This enables quick check/uncheck of checkboxes.

To use, select area of page with checkbox(es), and then right-click. You should see Check and/or Uncheck depending on the clicked or unclicked state of the checkboxes.

Please note that the extension does not work on all pages with multiple checkboxes installed. I tried using it on Google Mail and it turned out that the check and uncheck option in the right-click context menu does not become available after highlighting the part of the page that contains the checkboxes.

Other users have reported that the extension does not not work on sites such as eBay, or on forms that have more than one checkbox per row.

The extension has been last updated in June 2011, which could indicate that the developer has stopped development.