Free software to quickly and efficiently view, create, and edit PDF files.
Free utility to convert PDF files, extract texts from PDF files, in addition to many other features.
Free software that allows you to merge multiple pages of PDF documents into a single page.
Free and open-source graphical interface for pdftk (PDF Toolkit), a command-line tool used to manipulate PDF files.
Software for reading and printing PDF documents.

Utility to extract and merge pages from PDF files.