New Tab Override allows you to choose which page Firefox shows whenever you open a new tab. It can open any website you like, use your current homepage, display a stored local HTML file, or show a plain background color. It also includes options for the focus behavior and the tab position. Features

Set any website as your new tab page
Randomly select one page from multiple URLs separated by the pipe character (|)
Use your current homepage as the new tab page
Store a local HTML file in the extension and use it as new tab content
Use a custom background color for new tabs
Show the latest Mozilla news as the new tab page (German only)
Choose whether the focus should go to the address bar or the website
Control where new tabs are opened
Automatically add https:// when a URL is missing a protocol
Work with Firefox container tabs
Support dark mode in the settings interface
Support configuration via enterprise policies

Keyboard shortcuts The settings interface can be opened via the keyboard or from the menu. Use Shift + F12 to open it. You can also open it by entering newtab settings in the address bar or via the menu entry in the "Tools" menu. Languages The add-on is currently available in the following languages:

English
German
French (Thanks, SuperPat45 and Mozilla community!)
Simplified Chinese (Thanks, tiansh and Mozilla community!)
Spanish (Thanks, MissingUser and Mozilla community!)
Italian (Thanks, Mozilla community!)
Russian (Thanks, vanja-san!)
Polish (Thanks, WaldiPL!)
Dutch (Thanks, Tonnes!)
Turkish (Thanks, boranroni!)
Ukrainian (Thanks, Bergil32!)
Brazilian Portuguese (Thanks, Mozilla community!)
Swedish (Thanks, Sopor-!)
Indonesian (Thanks, rosatiara!)
Upper Sorbian (Thanks, milupo!)
Lower Sorbian (Thanks, milupo!)

Configuration via Enterprise Policies New Tab Override supports configuration via enterprise policies through storage.managed. Managed values override the same settings configured locally in the extension. Permissions New Tab Override requires several permissions to work properly. Some are mandatory, some are optional, and Firefox does not prompt for some of them. Mandatory permissions. New Tab Override will not work as intended without the following permissions: Access browser history This permission is required to prevent spammy moz-extension:// entries from being added to the browsing history every time you open a new tab. Access recently closed tabs This permission is required so that New Tab Override can remove internally closed new tab pages from Firefox's recently closed tabs list when the option to set the focus to the website is used. Access browser tabs This permission is required so that New Tab Override can focus the settings page if it is already open in another tab instead of opening it again. Read and modify browser settings This permission is required to change the position of new tabs and to use the option that automatically opens the current homepage as the new tab page. Optional permissions. This permission is not required to install and use New Tab Override, but the extension will request it at runtime when needed: Access data for www.soeren-hentzschel.at This permission is only required if you enable the option to show the latest Mozilla news as the new tab page. If enabled, New Tab Override reads the feed from www.soeren-hentzschel.at to display the latest news. Silent permissions. New Tab Override requires additional permissions, but Firefox does not prompt for the following: cookies The cookies permission is required to preserve container information when New Tab Override is used together with Firefox container tabs. menus The menus permission is required to provide a menu entry in the "Tools" menu for accessing the settings page. storage The storage permission is required to save settings such as your selected new tab page and to read enterprise-managed settings provided through Firefox policies.