Windows Backup & Restore: What to Keep from AppData?

There's no universal solution to this question. No one will ever give you a comprehensive answer because there are so many applications. Each application stores its preferences differently, and you have to know for each particular application what it stores in AppData to decide whether it's worth saving or not.

Let me give you a couple of examples:

• Firefox stores its profile and general settings in AppData\Roaming. I think it's worth saving, the browser will be configured the way it was, including bookmarks, and even open tabs will be restored.
  At the same time the data Firefox stores in AppData\Local are useless: there are different caches.
• Opera browser follows the same approach. You find its generic settings in AppData\Roaming and (mostly) throw-away data in AppData\Local.
  Yet if you used Opera Mail client, all the mails are saved in AppData\Local, thus you may want to keep your mail messages.
• Microsoft Outlook stores its personal files with mail in AppData\Local.
• foobar2000 audio player stores its settings and playlists in AppData\Roaming.

Usually data in AppData\Roaming are more important than in AppData\Local.

The main reason for your question is the wasted space in your backup so try to search in the AppData folder for all files that are bigger than 10 MB by typing size:>10MB (check for your command if you do not use the english version of Windows) into the search field. Now change the view to details and sort by folder.

By that you should be able to decide on yourself which folder contains important or useless data. Examples of folders containing useless data of considerable size:

• AppData\Local\Temp\
• AppData\Local\Microsoft\Windows\
• AppData\Local\CrashDumps\
• etc

I never found comparable folders inside of AppData\Roaming\ so it should remain in your backup.