WeTransfer - WeTransfer is a free service to send big or small files from A to B.
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.
ZetPDF - PDF library for .NET, Windows Forms, ASP.NET, Mono, WPF, Silverlight
PDFShift - Convert any HTML documents to high-fidelity PDF using a single POST request
PDF my URL - PDFmyURL turns any webpage or even complete website into PDF. Use our rest API in PHP, .NET, Ruby, Perl or any other programming language. Or convert webpages or even full websites directly in the browser!
Tcpdf - TCPDF: Open Source PHP Class for generating PDF documents