Free software for Windows that offers a practical solution to create, view, and edit PDF files.
Create PDF files from virtually any application.

Utility to extract and merge pages from PDF files.
Lightweight, fast, and open-source PDF viewer and toolkit that allows rendering PDF, XPS, and other formats with high fidelity and performance.
Free software for Windows that allows scanning and saving documents in PDF format.
Free and open-source graphical interface for pdftk (PDF Toolkit), a command-line tool used to manipulate PDF files.