Twpie is only able to POST tweets to Twitter i.e. it is not possible to read existing tweets, following users, etc.

However, since it has a limited feature set, it is the worlds fastest Twitter posting client for the iPhone and sending often used messages are as easy as pie.

Your sent messages are grouped and ordered by how often they are used and it comes preconfigured with tweets for known Twitter services such as @twye (tweet-what-you-eat), @twys, @having and @iquit.

Twpie does not transfer any data before you are actually sending a tweet and all previously sent tweets are stored locally and can be viewed while you have no internet connection.