PDF Split and Merge is a very simple, easy to use, free, open source utility to split and merge pdf files. It’s released in two versions: basic and enhanced. Includes a console and a GUI interface. pdfsam is an open source tool (GPL license) designed to handle pdf files. It requiers a Java Virtual Machine 1.4.2 or higher and it’s released in 2 versions, basic and enhanced.
pdfsam basic:
A simple tool designed to split and merge pdf files. With it’s simple and intuitive interface you can:

• split your pdf documents (into chapters, single pages, etc.).
• merge many pdf documents or subsections of them.
• exctract sections of your document into a single pdf document.
• save and load your environment to automatize your recurrent jobs.
• manage pdfsam settings and set an environment to load at start up.

pdfsam enhanced:
This is the enhanced version of pdfsam. In this version you’ll find all the basic features plus:

• encrypt your pdf files (RC40 bits, RC128 bits, AES128 bits) and set permissions on them.
• add a pdf cover or footer (or both) to your pdf documents.