WebSniffer - WebSniffer is an online tool to outlook HTTP request and response headers.
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.
HTTP-Repeater (HTTP/s Live Headers) (Beta) - HTTP-Repeater (HTTP/s Live Headers) (Beta) is a browser extension that lets you capture browser requests and repeat the process in a loop automatically.
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
Sky Live HTTP Headers - Sky Live HTTP Headers is an open-source browser extension that visually displays HTTP requests and response headers from every website you visit.
PDFShift - Convert any HTML documents to high-fidelity PDF using a single POST request