The renderer in MuPDF is tailored for high quality anti-aliased graphics. It renders text with metrics and spacing accurate to within fractions of a pixel for the highest fidelity in reproducing the look of a printed page on screen. (GPL)
Okular is an universal document viewer based on KPDF for KDE 4. (GPL)
Small python-gtk application, which helps the user to merge or split pdf documents and rotate, crop and rearrange their pages using an interactive and intuitive graphical interface. (GPL)
PDFCreator is a free tool to create PDF-files from nearly any Windows application. (GPL)
PDFedit is a free (and open source) editor for manipulating PDF documents. GUI version + commandline interface. (GPL)
PDFKeeper is an Open Source PDF Document Storage Solution that integrates with a compatible, relational database management system to provide an upload, index, and search solution for PDF documents. (GPL)
PDFsam basic is a free and open source, platform independent software designed to split, merge and rotate pdf files. (GPL)
PDFTK Builder is a free graphical interface to the Windows version of PDFTK making it much easier to use. (GPL)
Sigil is a multi-platform WYSIWYG ebook editor. Use Sigil to format and package your book into an EPUB. (GPL)
Linux - Windows - macOS
Sumatra PDF is a slim, free, open-source PDF viewer for Windows. (GPL)
Use the Open Source Software Directory to find the best open source and free software for at home or in business.
Advantages of open source software are: