Docupilot - Document Generation, Document Automation software
PdfPig - Read and extract text and other content from PDFs in C# (port of PDFBox)
Plumsail Documents - Document automation software that integrates with your favorite apps to generate documents seamlessly.
Document .Net - Gives you API to do everything with a document in PDF, DOCX, DOC, RTF, HTML and Text formats.
DocRaptor - As the only API powered by the Prince HTML-to-PDF engine, DocRaptor provides the best support for complex PDFs with powerful support for headers, page breaks, page numbers, flexbox, watermarks, accessible PDFs, and much more
PDFSharp - Office & Productivity and Development