caj2pdf is the original open-source CAJ converter. It detects the variant, converts CAJ and KDH files to PDF with bookmarks, reads the page count and table of contents, and can add CAJ bookmarks to a PDF printed from CAJViewer. HN files need two extra native libraries and often fail. It’s a script collection, not a PyPI package, and uses the GLWTPL license, which is not OSI-approved.
caj2pdfcaj2pdf is an open-source Python converter for CNKI CAJ files. How to install it, convert CAJ and KDH to PDF, read the page count and table of contents.