Tab Sync Lite od Ompio

Tab Sync Lite is a lightweight Firefox extension designed to synchronize browser tabs between multiple computers using your Firefox account. This simple solution allows you to save your current tab session and restore it on another device, helping you maintain workflow continuity.
Usage
Click the Tab Sync Lite icon in your browser toolbar to open the popup
Use the following buttons:
Save Current Tabs: Stores all your current tabs to sync storage
Download Tabs: Loads previously saved tabs from sync storage
Synchronize Tabs: Adjusts your current tabs to match saved session:
Closes tabs that aren't in your saved session
Opens tabs that are in your saved session but not currently open

Auto sync - after toggling on it syncs your tabs after 5 seconds and then saves them to your storage every 30 seconds