Hi Dan, you have two options here:

(1) Use Sync - works best with both computers running at the same time - see: How do I set up Sync on my computer?

(2) Copy over some files

If you need to give up your computer before you get the new one, you should make a backup of your active profile folder. See: Back up and restore information in Firefox profiles.

To transfer individual files:

(A) Saved Logins

These are saved in a pair of files: logins.json + key4.db

There also is a method to export saved logins to a CSV file if transferring logins.json + key4.db doesn't work. See: Export login data from Firefox / Import login and password data from a file.

See:

• About your important data and their files
• Restore bookmarks, passwords, and data from an old Firefox profile

(B) Bookmarks

Firefox saves automatic backups in the bookmarkbackups subfolder in your currently active profile folder. However, it might be simpler to create a new backup in an easily accessible location, such as your Windows desktop. See: Restore bookmarks from backup or move them to another computer.

Firefox also can generate a backwards-compatible/cross-browser "bookmarks.html" file. This is less complete than the backup format, but is good to have for emergencies because it is human-readable as a web page. See: Export Firefox bookmarks to an HTML file to back up or transfer bookmarks / Import Bookmarks from an HTML file.

Hi jscher2000, hope you're well. We have a question about bookmarks sync, with specific characteristics, please. We also purchased another computer, a laptop, and wish to benefit from the bookmarks sync between them. However, we're affraid of a backward syncing situation. How can we make sure we prevent that in our normal use?

For example, say we worked on the desktop for a week, and then need to use the laptop. What should we do when we turn the laptop on and open ff browser, if we wish to sync from the desktop to the laptop? Do we press the Sync button on the laptop? - or will that force a backward synching from the laptop to the desktop? If that's the case, than how do we sync? And the day after, from the now-updated-laptop to the desktop? Is the safest way to do it by turning the sync option off, and copying the bookmarkbackup folder from one updated computer to the other?

Also, this may complicate things a bit - We use the browser bookmarks in a non traditional way. It's kind of an archive for us. The .jsonlz4 file size in bookmarkbackups folder is 37MB. We remember reading somewhere before, the server backups stores files up to 10MB. So, the question is, does the large size or the bookmarks file will affect the synching process between computers?

Thank you very much!

Hi tef, you probably would be better off posting a new question because I don't use Sync between two different "desktop" installations of Firefox. In theory, they should merge the bookmarks from both together. However, it is possible for things to go wrong and your volume of bookmarks seems a little unusual.

https://support.mozilla.org/questions/new/firefox/form