PDFBinder is a free software that allows users to merge multiple PDF documents into a single file. The software has a simple and easy-to-use interface that enables users to add, delete, and reorder PDF pages as needed. Additionally, the software allows users to specify a custom page range to merge, making it easier to combine specific sections of PDF documents. Finally, PDFBinder supports drag-and-drop functionality, making it convenient for users to add their PDF files to the software.