# Extension not syncing settings across Firefox devices

**URL:** <https://discourse.mozilla.org/t/extension-not-syncing-settings-across-firefox-devices/144841>\
**Category:** Add-on Support\
**Created:** [July 17, 2025, 12:37am UTC](https://discourse.mozilla.org/t/extension-not-syncing-settings-across-firefox-devices/144841 "2025-07-17T00:37:33Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![rovmenpaul](https://avatars.discourse-cdn.com/v4/letter/r/a698b9/32.png) [@rovmenpaul](https://discourse.mozilla.org/u/rovmenpaul)\
**Post date:** [July 17, 2025, 12:37am UTC](https://discourse.mozilla.org/t/extension-not-syncing-settings-across-firefox-devices/144841/1 "2025-07-17T00:37:33Z")

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Hi Everyone,

I’m using a Firefox extension (a tab manager, if it matters) on both my Windows 11 laptop and Android phone.

I’m signed into the same Firefox account on both, and sync is enabled, but the extension settings and saved preferences don’t carry over between devices.

I thought Firefox Sync handled that or do extensions have to support it manually? Is there a way to force it or export/import the settings myself?

Thanks!

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<div class="post-metadata">

**Author:** ![juraj.masiar](https://sea1.discourse-cdn.com/flex001/user_avatar/discourse.mozilla.org/juraj.masiar/32/30587_2.png) [@juraj.masiar](https://discourse.mozilla.org/u/juraj.masiar)\
**Post date:** [July 17, 2025, 8:04am UTC](https://discourse.mozilla.org/t/extension-not-syncing-settings-across-firefox-devices/144841/2 "2025-07-17T08:04:25Z")

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Yes, extensions have to use Firefox Sync. storage explicitly, but it’s quite limited in terms of … everything, so many developers avoids it:

> **[storage.sync - Mozilla | MDN](https://developer.mozilla.org/en-US/docs/Mozilla/Add-ons/WebExtensions/API/storage/sync)**
>
> Represents the sync storage area. Items in sync storage are synced by the browser. The data is then available on all instances of the browser the user is logged into (for example, when using a Mozilla account on desktop versions of Firefox or a...

For example, it can handle only 100KB of data, one “entry” can have only 8KB and totally you can store only 512 entries.

So for extensions like tab/bookmark managers that needs to store hundreds (or more) tabs, is basically impossible to store it in sync. storage.

I’m using this storage for my [Auto Highlight](https://addons.mozilla.org/addon/auto_highlight/) and [Private Notes](https://addons.mozilla.org/addon/private_notes/) where I had to compress the data with LZMA compression and then encode with custom Base93 in order to squeeze the data in - not exactly a piece of cake 😃 .