If you have the fear of losing your Twitter tweets or if you are backup-holic, either the case here are two tools TwitterBackup and TweetBackup that will allow you to backup your tweets on any platform you are on and access them from anywhere as well.
TwitterBackup is a freeware tool written in Java, it downloads all your tweets and stores them in XML format. TwitterBackup requires your to enter your Twitter username and password. The backup can also be incremental, which means if you have done backup once it will add only newer tweets to it. This is faster than downloading the entire stream each time. TwitterBackup can be configured to run using proxy as well.
The second is TweetBackup. It is an online Twitter backup tool that can auto-backup your tweets daily and store all your Twitter data online. The setting up process is quick and you don’t even have to provide it with your Twitter password. All it asks for is your Twitter ID and email address.
You can access your data anytime you want and export it in RSS, Text or HTML format. Additionally it can also backup tweets of your friends. There is no limit on the number of profiles you can backup with TweetBackup.