iText is still an open source library. See http://sourceforge.net/p/itext/code/HEAD/tree/ if you want to take a look at the code. For Android, there is iTextG: http://sourceforge.net/projects/itextg/ You can find the source code for iTextG here: http://sourceforge.net/p/itextg/code/HEAD/tree/
You can also find our projects on Github: https://github.com/itext
If you find a place where somebody claims that iText is not open source, please let us know, so that we can ask those people to stop spreading non sense! The fact that I can point you at the source code of iText should be sufficient proof that those people are wrong.
This being said: the fact that iText is open source doesn't mean that the software can be used without having to buy a license. You can use iText for free if you obey the rules of the license: https://www.youtube.com/watch?v=NCwhEWEPV-E
It is very strange: the name "Free Software" was replaced by "Open Source Software" because developers wanted to make it clear that the "Free" in "Free Software" was not a synonym of "Gratis". Now that every one talks about "Open Source Software", many people thing that "Open Source Software" is a synonym of "Gratis Software".
This is explained in detail on the official iText web site: http://itextpdf.com/salesfaq
Note that droidtext is not an official iText product. It is a fork that is not endorsed by the creators of iText based on a version of iText that is not supported (it was declared End-of-Life years ago).