Glyph & Cog distributes Xpdf under two different licenses:
- An open source license - the GNU General Public License (GPL)
- A commercial license - see the source licensing page
The open source Xpdf project provides a PDF viewer (for the X Window System on Unix) and associated command line tools (which run on just about any platform that has a C++ compiler). This free version of Xpdf is licensed under the GPL (GNU General Public License), which allows anyone to use the source in their own applications, as long as they also distribute their application under the GPL.
For more details on the open source Xpdf project, visit the Xpdf web site.
While open source can be a contentious issue, it does have some advantages:
Try before you buy: if you want to know how the XpdfText® library will perform on your own PDF files, try out the pdftotext program from the Xpdf package - the core text extraction engine is the same. Similarly for the XpdfInfo library and the pdfinfo program, and so on.
Look over the source code: if you're thinking about licensing the Xpdf source code, download the Xpdf source and take a look.
If you want to use the stand-alone executables (pdftotext for example) with your application, you're free to do so. (To comply with the GPL, you'll need to distribute the Xpdf documentation along with the pdftotext executable - see the Xpdf README file for details.) Of course, for maximum performance, we recommend using our libraries or DLLs or building the Xpdf source code into your application.
We understand that open source isn't the right model for all applications. That's why we sell the libraries as well as commercial source licenses. Source licensing allows you to incorporate the Xpdf source code into your application, with no GPL restrictions.
Xpdf was created by Derek Noonburg, as the first open source PDF viewer. Its first public release (version 0.2) was in December 1995. It has been in continuous development since then, and now serves as the core of many of Glyph & Cog's products.
Poppler is an open source derivative of Xpdf, licensed under the GPL. Glyph & Cog does not own the copyright to the changes that the Poppler project has made to Xpdf, so we are not able to license Poppler.
If you're looking for a PDF viewer, take a look at the Xpdf source code, and particularly our XpdfWidget/Qt product.