Xpdf
open source PDF viewer
Xpdf is a free and open-source PDF viewer and toolkit based on the Qt framework. Versions prior to 4.00 were written for the X Window System and Motif.
Functions
Xpdf runs on nearly any Unix-like operating system. Binaries are also available for Windows. Xpdf can decode LZW and read encrypted PDFs. The official version obeys the DRM restrictions of PDF files, which can prevent copying, printing, or converting some PDF files. There are patches that make Xpdf ignore these DRM restrictions; the Debian distribution, for example, has these patches in place by default.
Xpdf includes several programs that don't need an X Window System, including some that 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, and PalmPDF on Palm OS and on Windows Mobile.
Begin with the source’s own compact description: “Xpdf” is open source PDF viewer. The dossier treats that line as a proposition to test through Xpdf, source and viewer, not as a finished interpretation.
Why this record matters
The phrase “open source PDF viewer” supplies a clear boundary for inquiry. It also exposes the unanswered questions: who defined that boundary, when it became stable and which sources sit outside it.
Vocabulary and entity names are the principal evidence signals here, because they determine the precision of every later search. The source revision retrieved here is dated Nov 18, 2025. The linked authority identifier is Q1570078. 2 of 2 selected statements include explicit references; 1 carry qualifiers and 0 use preferred rank.
A concise general-reference account can conceal disagreements about scope, terminology or the weight assigned to individual sources. The lead is largely declarative, so disagreement and counter-evidence require a deliberate search beyond the opening account. Authority statements aid reconciliation but still require their own references, qualifiers and ranks to be checked.
How to read it
Use the entry as an orientation point, then follow its citations and revision history. Names, dates and institutional relationships should be checked against the original record.
- Subject orientation
- Search vocabulary
- Locating named sources
The closest primary source, responsible institution and strongest cited specialist reference.
Three-step research path
- Establish the record: confirm the title “Xpdf”, its source revision and the description used here.
- Expand the search: follow Xpdf primary sources, Xpdf archive and Xpdf research across catalogues and specialist indexes.
- Test the account: compare the strongest cited source with the responsible institution’s current record and note any disagreement.
Questions for further research
- Which source most directly establishes the central claim about “Xpdf”?
- Which institution is responsible for the underlying evidence?
- Which cited source is closest to the event, object or claim?
Search terms from this dossier
This entry incorporates text from “Xpdf” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.