A library that allows you to generate PDF files on the fly
Edit by : iText is a library that allows you to generate PDF files on the fly.

iText is an ideal library for developers looking to enhance web- and other applications with dynamic PDF document generation and/or manipulation. iText is not an end-user tool. Typically you wont use it on your Desktop as you would use Acrobat or any other PDF application. Rather, youll build iText into your own applications so that you can automate the PDF creation and manipulation process. For instance in one or more of the following situations:
Due to time or size, the PDF documents cant be produced manually.
The content of the document must be calculated or based on user input.
The content needs to be customized or personalized.
The PDF content needs to be served in a web environment.
Documents are to be created in Batch process mode.
You can use iText to:
Serve PDF to a browser
Generate dynamic documents from XML files or databases
Use PDFs many interactive features
Add s, page numbers, watermarks, etc.
Split, Concatenate, and manipulate PDF pages
Automate filling out of PDF Forms
Add digital signatures to a PDF file
And much more...
In short: the iText classes are very useful for people who need to generate read-only, platform Independent documents containing text, lists, tables and images; or who want to perform specific manipulations on existing PDF documents. The library is especially useful in Combination with Java(TM) technology-based Servlets; theres also a .NET port available: iTextSharp (written in C#).

iText requires JDK 1.4. Its available for free under a multiple license: MPL and LGPL. you can free download iText 3.1.5 now.