Download the official PDF-4 installer (a 15-20 GB file). This is not the database itself; it is the installer. The actual database is unlocked with a USB hardware key (dongle) or a license file.
While the entire database is not free, there are a few legitimate ways to access specific data at no cost: PDF-4/Minerals | Mineral Phase Identification & XRD Data - Icdd Pdf-4 Database Free Download
The PDF-4 product line, including , PDF-4/Minerals , and PDF-4/Axiom , is designed for advanced X-ray diffraction (XRD) phase identification. Download the official PDF-4 installer (a 15-20 GB file)
register on the ICDD portal, download the dataset (or a lightweight sample), and begin experimenting with the sample code above. Whether you’re building a next‑generation OCR engine, a smart document classifier, or an accessibility checker, PDF‑4 offers the real‑world variability you need to make your solution robust. While the entire database is not free, there
: Many university libraries or research centers (such as the UCI Science Library
Many university libraries, such as the University of California, Irvine (UCI) , provide terminal access to the PDF-4+ database for their students and faculty at no personal cost.