There is only one file type that uses the .WEBBOOKMARK extension:
Safari Web Bookmark File
A WEBBOOKMARK file is a bookmark file created by Safari, macOS's default web browser. It contains information about a bookmarked webpage, including the page's title, URL, and bookmark group. WEBBOOKMARK files are used to save and organize a user's bookmarks.
Safari users can use the browser's Bookmarks feature to save and organize links to their favorite or important webpages. These links are saved in WEBBOOKMARK files. Users can view and organize their bookmarks by selectingin Safari.
Safari saves WEBBOOKMARK files in the following directory by default:
Updated: August 1, 2020