There is a category of web tools I will call document converters — the ones that take a Word file or a PDF and give you Markdown or HTML back. They are everywhere. And they are almost all bad.

The problem is not that the conversion quality is bad in absolute terms (though it often is — lost table borders, heading hierarchies flattened to bold text, footnotes silently dropped). The problem is structural: every converter falls into one of two failure modes. Either it is a simple HTML-to-Markdown transformer that cannot read binary document formats at all, or it is a mature tool with real parsing logic that you have to install on your machine.

Pandoc is the gold standard of the second category. It reads 14 document formats and writes 8 more. It handles citations, Lua filters, custom templates, footnotes, and arbitrary nesting levels of headings and lists.…