Sumatra PDF - Sumatra PDF is a slim PDF/DjVu/EPUB/XPS/CHM/CBR/CBZ/MOBI viewer for Windows.
RoxyApps PDF Merge Tool - Merge multiple files of different formats in a single PDF file
calibre - Ebook manager, viewer & converter
PDFMerge - PDF Split and Merge tool is implemented using the PdfSharp library and is either GUI or command...
Okular - Okular is a universal document viewer based developed by KDE.
PDFMate Free PDF Merger - PDFMate Free PDF Merger works as a PDF Joiner, PDF combiner, PDF breaker, image to PDF converter and PDF encryptor. With PDF Merger, you can batch merging pdf files, combining specified pages or converting scanned image file to create new PDF file.