Tab Group Syncer by Sudhir Babu Nakka

If you wanted this and/or think this helps you - consider supporting it (The funds are forwarded to a walking stick for blind donation target I have)
https://ko-fi.com/sudhirnakka

I will maintain it until firefox officially introduces tab group sync.

Once installed, you can provide a name for your current device. This will show up on your other devices during sync.
Click on the plugin icon - you will see a popup where
* you can provide a name for your device
* you will see a list of your devices and any tab groups available from that device
* select/deselect tab groups you want to be pulled/synced and trigger a sync

The plugin uses firefox official sync service and storage - so it is extremely secure and the data will be in firefox control as it is with existing sync.

Plugin is open source under MIT license. Feel free to play with it, contribute to it or make a version of your own.
https://github.com/sudhir-asuracore/firefox-tab-group-sync

Update September 1. 2026: I am still tracking firefox mobile API to become available. In-order to make tab groups sync work with mobile aswell - we will need Mozilla to make few underlying API available.

Update September 10, 2026:
* Still tracking firefox mobile API to become available for tab group sync across mobile devices
• On-Demand "Pull" & Reactive Sync:
• Added an instant Pull button alongside Push to immediately fetch and refresh remote device snapshots without waiting for Firefox Sync's background cycle.
• Added active storage.onChanged background listeners to automatically reflect incoming cloud changes.
• Push & Pull buttons now feature a clean built-in progress indicator to avoid popup layout shifts.
• Advanced Sync & Diagnostics Modal:
• Storage Quota Meter: Real-time gauge monitoring browser.storage.sync usage against Firefox's 100 KB limit.
• Sync Diagnostics: View last push status, sync timestamps, and error diagnostics at a glance.
• Offline Backup & Restore: Direct Export JSON and Import JSON tools to backup or migrate tab groups between devices instantly with zero cloud latency.
• First-Time / Multi-Device Sync Helper:
• Added an actionable troubleshooting banner advising users to verify that "Add-ons" is checked in Firefox Sync settings and demonstrating how to trigger "Sync Now".
• UI & Icon Overhaul:
• Replaced the extension icon set with a high-resolution, transparent circular design across all sizes (16px, 32px, 48px, 64px, 128px).
• Removed the dynamic canvas background fill from the toolbar icon to keep the icon transparent and crisp.
• Added a direct ★ Rate link in the popup footer pointing to the Firefox Add-ons store.