PDFShift - Convert any HTML documents to high-fidelity PDF using a single POST request
PDFium - The C# PDF Library to Create and Edit PDF documents in .
Tcpdf - TCPDF: Open Source PHP Class for generating PDF documents
Document Cyborg - Easily save a web page as a document (PDF, WORD, EPUB, ODT, RTF or Text)
pdflayer - Free, powerful HTML to PDF API supporting both URL and raw HTML conversion. Unlimited document size, lightning-fast and compatible PHP, Python, Ruby, etc.
PDF Shaper - a collection of PDF tools and utilities to modify and optimize your PDF documents and its content