The article celebrates the 20th anniversary of pandoc, a document conversion tool written in Haskell. The author, John MacFarlane, recounts the project's history, from its humble beginnings as a Markdown parser to its current status as a widely-used tool supporting over 50 document formats. Pandoc's development was driven by the author's own needs and collaborations with other programmers. The tool has become an essential part of many workflows, including academic writing and data science.