PoDoFoBrowser is developed with Qt4 by the same author of PoDoFo, a gui for editing the object structur of PDF files directly.
Scribus is an Open Source program that brings award-winning professional page layout to Linux/UNIX, Mac OS X, OS/2 Warp 4/eComStation and Windows desktops with a combination of “press-ready” output and new approaches to page layout.
Underneath the modern and user friendly interface, Scribus supports professional publishing features, such as CMYK color, separations, Spot Colors, ICC color management and versatile PDF creation.
calibre is a free and open source e-book library management application developed by users of e-books for users of e-books
Comment is a PDF annotator (tailored to the author’s needs as a mathematician who wants to comment articles and save the comments for later reference with the pdf files).
PoDoFo is a library to work with the PDF file format. The name comes from the first letter of PDF (Portable Document Format). A few tools to work with PDF files are already included in the PoDoFo package.
The PoDoFo library is a free, portable C++ library which includes classes to parse PDF files and modify their contents into memory. The changes can be written back to disk easily. The parser can also be used to extract information from a PDF file (for example the parser could be used in a PDF viewer). Besides parsing PoDoFo includes also very simple classes to create your own PDF files. All classes are documented so it is easy to start writing your own application using PoDoFo.
PoDoFo is written in C++ and the code was sucessfully compiled under Unix, Mac OS X and Windows.