SingleFile
Web Extension for saving a copy of complete web page in a single file
...You can click again on the button to cancel the action when processing a page. Open the context menu by right-clicking the SingleFile button in the extension toolbar or on the webpage. It allows you to save the current tab, the selected content, the selected frame. With auto-save active, pages are automatically saved every time after being loaded (or before being unloaded if not). Right-click on the SingleFile button and select "Manage extension" (Firefox) / "Options" (Chrome) to open the options page.