Firefox json file location

Here is where to find bookmarks of firefox. If you want to save bookmarks just save json file.

C:\Users\<user name>\AppData\Roaming\Mozilla\Firefox\Profiles\<profile folder>\bookmarkbackups

The AppData folder is a hidden folder, to show hidden folders: open a Windows Explorer window, choose "Organize/ Folder and Search Options/ Folder Options/ View/ Show hidden files and folders"