LastPass has updated its bookmark sync add-on for Firefox, Xmarks, to version 4.0.0. The major standout feature in this new release is a new feature called Repair, which allows Xmarks to effortlessly roll back the last sync operation should it prove unsuccessful or introduce unwanted changes.

Xmarks is an add-on that is designed to synchronise bookmarks across a number of browsers, devices and computers with the minimum of fuss. It’s available as a free add-on for most major browsers for syncing across multiple platforms and computers, while there is also a Premium version available with extra features, including support for mobile devices.

The Xmarks sync feature works by assuming that bookmarks don’t change unless Xmarks itself is aware of the fact. This means Xmarks is constantly working in the background making small changes to your bookmarks database, and if changes occur that it’s not aware of, then problems arise.

The Repair option – available from the Advanced tab of Xmarks’ settings dialog box – creates a snapshot of the local bookmarks folder, sets the bookmarks to match those on the server and then finally adds back any local bookmarks that aren’t found on the server. It’s also capable of repairing the Places Database, which can cause corrupt bookmarks database errors in Xmarks.

Xmarks for Firefox 4.0.0 is available as a free download for Windows, Mac and Linux users running Firefox. There are also versions of Xmarks for Chrome, Internet Explorer and Safari, although as yet the Repair feature isn’t available on any of these platforms. Premium users can also access their bookmarks on a range of portable devices, including iPhone and Android.