Apache PDFBox - The Apache PDFBox™ library is an open source Java tool for working with PDF documents.
PDF24 PDF Creator - Create PDF and convert documents to PDF for free with the free PDF24 PDF Creator.
PortableSigner - PortableSigner is a signing (with X.509 certificates) program for PDF files.
DocHub - Edit, send & sign PDFs online for free.
Foxit PhantomPDF - Edit PDF files with our feature-rich PDF Editor. Download Foxit PDF Editor to convert, sign, scan / OCR & more. A speedy PDF Editor alternative to Adobe Acrobat.
Wondershare PDFelement - All-in-one PDF editor