Inkscape is a free and open-source vector graphics editor software.

PDFsam Basic extremely useful tool for splitting and merging PDFs in a configuration that suits you.

PDF Studio is a commercial software program for end-users to create, review, annotate, and edit PDF (Portable Document Format) documents.

jPDF Tweak is a Java Swing application that can combine, split, rotate, reorder, watermark, encrypt, sign, and otherwise tweak PDF files.

LibreOffice is a full-featured office productivity suite that provides a near drop-in replacement for Microsoft Office.

Adobe Acrobat Reader DC is the industry standard for viewing, printing, signing and commenting on PDF documents.

Master PDF Editor is а complete application for editing PDF documents and PDF files for Mac OS X, Windows and Linux.