The Xpdf viewer
|Initial release||December 12, 1995|
|Stable release||3.03 / August 16, 2011|
|License||GNU GPL or proprietary|
Xpdf is an open-source PDF viewer for the X Window System and Motif. Xpdf runs on practically any Unix-like operating system. Xpdf can decode LZW and read encrypted PDFs. The official version obeys the DRM restrictions of PDF files, which may prevent copying, printing, or converting some PDF files. There are patches which make Xpdf ignore these DRM restrictions.
Xpdf includes several programs that don't need an X Window System, including some which extract images from PDF files or convert PDF to PostScript or text. These programs run on DOS, Windows, Linux and Unix.
Xpdf is also used as a back-end for other PDF readers frontends such as KPDF and GPDF, and its engine, without the X11 display components, is used for PDF viewers including BePDF on BeOS, '!PDF' on RISC OS, on PalmPDF on Palm OS and on Windows Phones.
See also 
- Poppler, a GPL-licensed fork of the xpdf-3.0 rendering library designed for easier reuse in other programs
- List of PDF software