.JSONLZ4 File Extension
File TypeCompressed Firefox Bookmarks Backup File
What is a JSONLZ4 file?
Compressed bookmark backup file created and used by Firefox, a web browser; contains data describing all of the bookmarks used by the Firefox user profile; similar to the .JSON file used by Firefox.
The JSONLZ4 file can be used to recover bookmarks lost when they are cleared with a browser version update. You can find them in the "bookmarkbackups" folder, which is located in the Firefox user profile directory. The name of the file indicates the day it was created.