PDF Clown - PDF Clown is an open-source general-purpose library for manipulating PDF documents through multiple abstraction layers, rigorously adhering to PDF 1.7 Specification
CutePDF - CutePDF is a simple but entirely powerful PDF files creator, converter, and virtual printer.
iTextPDF - iText offers flexible tools for PDF creation, editing and inspection.
FoxIt - FoxIt offers solutions to read and edit PDFs from PCs or mobiles.
Document .Net - Gives you API to do everything with a document in PDF, DOCX, DOC, RTF, HTML and Text formats.
Adobe Acrobat DC - Make your job easier with Adobe Acrobat DC, the trusted PDF creator. Use Acrobat to convert, edit and sign PDF files at your desk or on the go.