Open Source

Glyph & Cog distributes Xpdf under two different licenses:

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:

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.

About Xpdf

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.

About Poppler

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.