How can I download the contents of my LiveJournal, Foursquare, Twritter account?

Question

API

I would like to download the contents of my accounts (all entries) LiveJournal, Foursquare and Twritter into something structured like xml, json, sqlite.
At the same time, the download script itself must be available in the source code, that is, third-party web services that need to specify their password are not suitable.
If there is no ready-made script, a library is suitable, to which it is enough to attach a simple harness.