Firefox Sync
Developer(s)Mozilla Corporation, Mozilla Foundation
Initial releaseDecember 21, 2007 (2007-12-21)[1]
Stable releaseN/A (part of Firefox) [±]
Operating systemCross-platform
TypeBrowser synchronizer

Firefox Sync, originally branded Mozilla Weave,[2] is a browser synchronization feature for Firefox web browsers. It allows users to partially synchronize bookmarks, browsing history, preferences, passwords, filled forms, add-ons, and the last 25 opened tabs across multiple computers.[3] The feature is now included in Firefox and is being implemented in Thunderbird.[4]

It keeps user data on Mozilla servers, but according to Mozilla the data is encrypted in such a way that no third party, not even Mozilla, can access user information.[5] It is also possible for the user to host their own Firefox Sync servers, or indeed, for any entity to do so.[6]

Firefox Sync was originally an add-on[7] for Mozilla Firefox 3.x and SeaMonkey 2.0, but it has been a built-in feature since Firefox 4.0[8] and SeaMonkey 2.1.[9]

Firefox Sync is built on top of Firefox Accounts as of Firefox 29, and therefore Firefox 29 and later cannot sync with Firefox 28 and earlier.[10]

Firefox Home

Main articles: Firefox Home and Firefox for iOS

Firefox Home was a companion application for the iPhone and iPod Touch based on the Firefox Sync technology. Firefox Home was not considered a web browser, as it would launch pages in either an embedded viewer or by switching to the Safari app.[11][12] In December 2014, Mozilla announced Firefox for iOS, a version of the Firefox browser for iOS,[13][14] which includes Firefox Sync support for syncing Firefox's browsing history, bookmarks, and recent tabs.

Sync Server

Mozilla also offers a synchronization server application for use with Firefox Sync, for users and businesses that prefer to host their own synchronization data.[6]


  1. ^ Beard, Chris (December 21, 2007). "Introducing Weave". Mozilla Labs. Mozilla. Retrieved 2014-05-11.
  2. ^ dknite (May 19, 2010). "Firefox Sync 1.3 is coming!". Retrieved 2010-05-28.
  3. ^ Cabello, Percy (January 28, 2010). "Weave 1.0 now available for download". Mozilla Links. Mozilla. Archived from the original on December 21, 2010. Retrieved 2010-02-06.
  4. ^ "Firefox Sync is working in Thunderbird way ahead of schedule". Twitter. 2022-07-22. Retrieved 2022-07-23.
  5. ^ "How do users know their data is secure?". MozillaWiki. Mozilla. February 6, 2010. Retrieved 2010-02-06.
  6. ^ a b "Run your own Sync-1.5 Server". Mozilla. Retrieved 16 September 2019.
  7. ^ "Firefox Sync for Firefox 3.5/3.6". Mozilla Labs. Mozilla. Archived from the original on 2011-10-15. Retrieved 2012-01-19.
  8. ^ "Get Syncing with Firefox 4". Mozilla Services. 2011-03-22. Retrieved 2011-08-26.
  9. ^ "What's New in SeaMonkey 2.1". SeaMonkey project. Retrieved 2011-08-26.
  10. ^ "Firefox Sync". Mozilla. Archived from the original on 2015-05-07. Retrieved 2015-02-17.
  11. ^ Dolecourt, Jessica (May 27, 2010). "Firefox Home: A not-quite Firefox iPhone app". Archived from the original on October 23, 2012. Retrieved 2010-06-02.
  12. ^ "Firefox Home Coming Soon to the iPhone". May 26, 2010. Retrieved 2010-06-03.
  13. ^ "App Store Review Guidelines". 12 September 2019. Archived from the original on 2020-03-04. Retrieved 2020-11-11. 2.5.6 Apps that browse the web must use the appropriate WebKit framework
  14. ^ Porter, Jon (2020-09-18). "Here are the browsers iOS 14 now lets you set as default". The Verge. Retrieved 2020-11-11. All browsers are still required to use WebKit