The PDFBinder tool is a free tool for the most part because it has a GNU license which means it has a general public use (GPU) or general public license (GPL) so you are able to use it for free to study run share modify but not sell it.
Collect Your Files Together Into One File
The PDFBinder was created by Joern Shou-Rode. The tool allows you to merge a number of different PDF files into a portable binder which essentially binds your PDFs into one file. You are then able to transport the file and open it up again at another location with your PDFBinder. It is similar to a zip tool except that it doesn't condense your files it simply places them all in one place. Just like a binder you may remove PDF files as you see fit. You may mix up PDF files with other file types to make a single file.
Conclusion - You Do Not Have To Use Expensive Software To Carry Your Files
The PDFBinder is a time saver and a convenience tool. Instead of having to use slow and/or expensive software to move your files around or to collect your files together you may simply use this binder. You may use it for presentations because you may create a portfolio file with it if you wish.