Software that allows you to organize, edit, and manage pages of PDF documents.
Free software for Windows that allows scanning and saving documents in PDF format.
Lightweight, fast, and open-source PDF viewer and toolkit that allows rendering PDF, XPS, and other formats with high fidelity and performance.

Utility to extract and merge pages from PDF files.
Free and open-source graphical interface for pdftk (PDF Toolkit), a command-line tool used to manipulate PDF files.
Create, edit, convert, and view PDF documents.