CodeTriage - Help out your favorite open source projects and become a better developer while doing it.
PDFCrowd - Pdfcrowd is a Web/HTML to PDF online service. Convert HTML to PDF online in the browser or in your PHP, Python, Ruby, .NET, Java apps via the REST API.
24 Pull Requests - 24 Pull Requests is a little project to promote open source collaboration during December.
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
Gitpay - Add bounties to solve Git issues from projects.
PDFShift - Convert any HTML documents to high-fidelity PDF using a single POST request