PortableSigner - PortableSigner is a signing (with X.509 certificates) program for PDF files.
PDF Joiner - This online tool allows you to join several PDF documents into a single file, free of charge.
PDF24 PDF Creator - Create PDF and convert documents to PDF for free with the free PDF24 PDF Creator.
PDFChef Merge PDF - PDFChef Merge PDF is an online tool that allows you to merge multiple PDf files into one quickly and securely.
iSafePDF - iSafePDF is a free open source PDF protection software.
PDFill - Open, View, Edit, Save and Print PDF Documents without Adobe Acrobat