On this page, you will find a few quick demos of what is possible with iText's libraries. We have included a couple of demos for the Android version, PDF splitting and merging as well as XFA and XML Worker. If you'd like more theoretical background, feel free to browse around some more on the developers' domain of this website.
Here are some servlets taken from the second edition of the 'iText in Action' book:
Creating PDF from JSP (don't do this, use a servlet instead)
XFDF example (*)
FDF example (*)
The examples marked with (*) require a full-blown PDF viewer as browser plug-in. They will work when using Adobe Reader, but not necessarily with other applications such as PDF.js or Chrome PDF viewer.