How to import Firefox bookmarks into Save This One

Firefox puts two different operations beside each other: Backup creates JSON/JSONLZ4 for restoring Firefox, while Export Bookmarks to HTML creates a portable file for another service. Save This One needs the HTML export. Renaming a .jsonlz4 file to .html does not convert it.

Export HTML, not a Firefox restore backup

1. In desktop Firefox, open the menu and choose Bookmarks → Manage bookmarks. (Ctrl/Cmd+Shift+O also opens the Library.)
2. In the Library toolbar, choose Import and Backup.
3. Select Export Bookmarks to HTML….
4. Save bookmarks.html, Firefox's default filename.

Mozilla's current export guide documents both the steps and the distinction: JSON/JSONLZ4 is a Firefox-only restore backup and HTML is the transfer format. Firefox mobile relies on Firefox Sync for this process; sync to desktop, let it finish, then export.

Why not use Backup?

A Firefox JSON restore is designed to reconstruct Firefox-specific state and can replace bookmarks in a Firefox library. Save This One does not accept it. HTML is interoperable, but that portability has a cost: Firefox-specific metadata is not guaranteed to survive the export. In particular, do not assume Firefox bookmark tags, keywords/shortcuts, sidebar settings, favicons, or a bookmark's visit history will be represented in a way this importer preserves.

How the portable fields map

In Firefox's HTML	In Save This One
HREF URL	Imported if it uses http or https
Anchor text	Bookmark title
ADD_DATE / usable modification date	Original save date
Custom folder path	One normalized tag: Projects/Atlas → projects-atlas
Bookmarks Toolbar/Menu/Other container	No tag
Separator	Ignored; it has no URL
place: query, file:, or javascript:	Skipped as a non-web link
Duplicate URL	Skipped without merging metadata into the existing bookmark

Firefox's Tags view is not a normal folder hierarchy. If tags are central to your organization, inspect the HTML before migrating: search it in a text editor for a distinctive Firefox tag. The reliable promise here is folder-path conversion, not reconstruction of every Places database feature.

Preview and diagnose before import

Choose bookmarks.html in the Save This One importer. The preview gives you a valid-link count, tags, sample titles, a save-date range when available, and skipped rows. Nothing is uploaded until you press Import.

• The preview is empty: confirm the file contains <A HREF= links and that you did not choose .json or .jsonlz4.
• The count is lower than Firefox: separators, smart place: bookmarks, local files, bookmarklets, and repeated URLs explain common differences.
• A folder tag is absent: system containers are intentionally dropped. Any path containing Bookmarks Toolbar, Bookmarks Menu, or Other Bookmarks is treated as structural rather than topical.
• The file is very large: one file must be no more than 25 MB; only its first 5,000 valid bookmarks are available to import.

After import, search for one bookmark from each custom folder depth, open a very old link, and confirm its displayed date. Compare the final imported-plus-skipped result with the preview rather than expecting every Library row to be a portable URL. Keep both the HTML and, if you want a full Firefox recovery option, a separate Firefox JSON backup.

The tradeoff

Move when you want links discoverable independently of Firefox and prefer flat tags to a Places folder tree. Keep Firefox's own library as your source of truth if bookmark keywords, exact hierarchy, browser history, or Firefox Sync are essential. The migration is only a copy. For links you save afterward, Firefox users can use the address-bar method; the current Save This One extension targets Chromium browsers.