PDF program libraries

PDFtk - The PDF Toolkit
PDFtk - Wikipedia, the free encyclopedia
PDFtk is a front end to the iText library

iTextSharp, a .NET PDF library | SourceForge.net

(Affero GNU)

Home of PDFsharp and MigraDoc Foundation - PDFsharp & MigraDoc
Licensing - PDFsharp & MigraDoc
PDFsharp and MigraDoc Foundation are published under the MIT License.

wkhtmltopdf

"wkhtmltopdf and wkhtmltoimage are open source (LGPLv3) command line tools to render HTML into PDF and various image formats using the Qt WebKit rendering engine. These run entirely "headless" and do not require a display or display service."

Syncfusion Ebooks | PDF Succinctly