XFA Worker is an add-on of iText 5 Suite, and only available with a commercial license.
Features & benefits
Dynamic PDF XFA forms for an optimal user experience.
XFA technology underpins a change in the way businesses as well as governmental offices are currently managing data.
XFA’s dynamic features allow your PDF forms to grow and reformat themselves depending on the data entered.
For instance, in a tax form your PDF file can generate new fields based on user responses.
Convert and protect. XFA Worker lets you program dynamic PDFs as well as convert them into static, protected PDF files for security reasons.
XFA Worker Tutorial Video
Have you already considered iText 7?
While iText 5 already gained fame as one of the world's most widely used and documented SDKs for adding rich PDF functionalities to applications, iText 7 has upped the ante. It offers the following advantages over iText 5:
Superior performance: the perfect technology for high-volume document projects.
Easier PDF program creation and editing through a greatly improved document model, lay-out engine, and APIs.