Editor: Xpdf is an open Source Viewer for Portable Document Format (PDF) files. (These are also sometimes also called 'Acrobat' files, from the name of Adobe's PDF software.) The Xpdf project also includes a PDF text extractor, PDF-to-PostScript converter, and various other utilities.
Xpdf runs under the X Window System on UNIX, VMS, and OS/2. The non-X components (pdftops, pdftotext, etc.) also run on Win32 systems and should run on pretty much any system with a decent C++ compiler.
Xpdf is designed to be small and efficient. It can use Type 1, TrueType, or standard X fonts.
Xpdf is licensed under the GNU General Public License (GPL), version 2. In my opinion, the GPL is a convoluted, confusing, ambiguous mess. But it's also pervasive, and I'm sick of arguing. And even if it is confusing, the basic idea is good.
In order to cut down on the confusion a Little bit, here are some informal clarifications:
* If you are redistributing unmodified copies of Xpdf (or any of the Xpdf tools) in binary form, you need to include all of the documentation: README, MAN Pages (or help files), and COPYING. The README file contains a pointer to a web page with the source code, which satisfies the GPL requirement as far as I am concerned. You are, of course, welcome to distribute the source code as well.
* If you are incorporating the Xpdf source code into another program, and you are distributing that program, you'll need to release your program under the GPL, which means you'll have to make the full source available. This also applies if you are making changes to the Xpdf tools.
