Easiliy manage your sites 404 page(s) from the content context menu. (For Umbraco 7.3 and higher)
The page not found manager will extend the context menu for admins with a new option “404 page”. The new option will open a dialog where you are able to select a 404 page for the current page and it’s children (either by searching or selecting a page from the content tree). So you can also setup multiple 404 pages (in case you have a multilingual site or an umbraco instance running multiple sites). Since it works this way it’s more versatile then the standard umbraco 404 page setup.
You can also fetch it from nuget: