What are some alternatives?
When comparing mergepdf.net and PDFTK Builder, you can also consider the following products
Merge PDF - Merge PDF is a user friendly PDF Reader.
PDFsam - PDFsam Basic, a free, open source, multi-platform software designed to split, merge, extract pages, mix and rotate PDF files
RoxyApps PDF Merge Tool - Merge multiple files of different formats in a single PDF file
Adobe Acrobat DC - Make your job easier with Adobe Acrobat DC, the trusted PDF creator. Use Acrobat to convert, edit and sign PDF files at your desk or on the go.
PDFMerge - PDF Split and Merge tool is implemented using the PdfSharp library and is either GUI or command...
PDF-Shuffler - PDF-Shuffler is a small python-gtk application, which helps the user to merge or split pdf...