Apache PDFBox - The Apache PDFBox™ library is an open source Java tool for working with PDF documents.
DocGen - Static website generator
iTextPDF - iText offers flexible tools for PDF creation, editing and inspection.
LogicalDOC - A document management system such as LogicalDOC can help your organization better manage business processes and put order in the chaos of documents every day run your business.
IronPDF - SDK for creating and editing PDFs.
openSourceCM - Web-based legal document processing and contract management