Pandoc is a document-conversion program that can translate among a myriad of formats, including LaTeX, HTML, Office Open XML (docx), plain text, and Markdown. It is also extensible by writing Lua filters that can manipulate the document structure and perform arbitrary computations. Pandoc has appeared in various LWN articles over the years, such as my look at Typst and at the importance of free software to science in 2025, but we have missed providing an overview of the tool. The February release of Pandoc 3.9, which comes with the ability to compile the program to WebAssembly (Wasm), allowing Pandoc to run in web browsers, will likely also be of interest.