If you are looking to edit PDF files, there are quite a lot of alternatives. Here are the most powerful solutions:
Inkscape: Inkscape is professional quality vector graphics software. It uses vector graphics to open and edit PDF files, enabling a full and powerful editing experience.
LibreOffice Draw: LibreOffice is a free and open source software suite much like Microsoft Office. It’s a good option to edit PDF files if you have already installed LibreOffice suite.
Apache OpenOffice Draw: Similar to Inkscape and LibreOffice Draw in that it is a drawing tool that you can use to edit PDF files. More consistent than LibreOffice Draw.
PDFedit: PDFedit is a free open source pdf editor and a library for manipulating PDF documents.
PDFsam Basic: PDFSam basic is a PDF file editor that supports merging, splitting and editing of PDF files. It is also an open source PDF editor.