Zotero uses customized, platform-specific versions of the pdfinfo and pdftotext utilities from the open-source Xpdf project for PDF indexing. Specifically, Zotero uses modified binaries of pdfinfo and pdftotext on Windows to prevent the command-prompt window from appearing at indexing time, and a custom build of pdfinfo on all platforms that supports writing to a text file (see source code).

If installation via the Search tab of the Zotero preferences window fails, the easiest solution is to install the tools from another computer running the same OS and copy the files over from the Zotero data directory on that computer.

Users wishing to build the Xpdf tools manually can do so by building the tools and either placing the binaries directly in the Zotero data directory or linking to them from there. Either way, platform-specific files must be created in the Zotero data directory, conforming to the format pdfinfo-{platform} and pdftotext-{platform}, where {platform} is “Win32”, “MacIntel”, “MacPPC”, “Linux-i686”, etc. (To determine your current platform, open the Firefox Web Console and type navigator.platform.) The Windows executables require the .exe extension (e.g., pdftotext-Win32.exe). Text files containing the installed version number should also be created with filenames in the format {executable-name}.version (e.g., pdftotext-MacIntel.version).