This action for Apple’s Automator allows the user to archive a series of web pages as PDF documents in a given workflow. As of version 6.0, the heavy lifting is now done in a small commandline app called url2pdf, which is wrapped in an AppleScript-based action.
Download URLs as PDFs 6.2 was tested with OS X Mountain Lion and should work with more recent OS versions. No new development is planned for this action, so you might consider another option, like wkhtmltopdf.
This action (along all previous versions) is available from Gumroad for whatever price you see fit above a minimum of $2.
Source code for URL2PDF and Download URLs as PDFs is available on Github.